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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v4 4/5] x86/PV: use generic emulator for privileged instruction handling
There's a new emulator return code being added to allow bypassing
certain operations (see the code comment).
Another small tweak to the emulator is to single iteration handling
of INS and OUTS: Since we don't want to handle any other memory access
instructions, we want these to be handled by the rep_ins() / rep_outs()
hooks here too.
And then long-mode related bits now get hidden from the guest. This
should have been that way from the beginning, but becomes a requirement
now as the emulator's in_longmode() needs this to reflect guest view.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v4: Rename priv_op_to_linear() to pv_emul_virt_to_linear() and change
its return type. Refuse system segments and set just one of L and
DB in 64-bit mode case of priv_op_read_segment(). Have
pv_emul_cpuid() return X86EMUL_EXCEPTION in the CPUID faulting
case. Add EFER behavioral change to description.
v3: Re-base. Do away with the special case pointer checks on the ->read
and ->write methods in OUTS and INS handling. Clear EFER.LM* bits
for 32-bit guests (to avoid the emulator's in_longmode() returning
a wrong result). Introduce and use ->validate() hook. Make
formatting more consistent.
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -697,16 +697,13 @@ static inline void do_guest_trap(unsigne
pv_inject_event(&event);
}
-static void instruction_done(
- struct cpu_user_regs *regs, unsigned long eip, unsigned int bpmatch)
+static void instruction_done(struct cpu_user_regs *regs, unsigned long eip)
{
regs->eip = eip;
regs->eflags &= ~X86_EFLAGS_RF;
- if ( bpmatch || (regs->eflags & X86_EFLAGS_TF) )
+ if ( regs->eflags & X86_EFLAGS_TF )
{
- current->arch.debugreg[6] |= bpmatch | DR_STATUS_RESERVED_ONE;
- if ( regs->eflags & X86_EFLAGS_TF )
- current->arch.debugreg[6] |= DR_STEP;
+ current->arch.debugreg[6] |= DR_STEP | DR_STATUS_RESERVED_ONE;
do_guest_trap(TRAP_debug, regs);
}
}
@@ -1336,7 +1333,7 @@ static int emulate_invalid_rdtscp(struct
return 0;
eip += sizeof(opcode);
pv_soft_rdtsc(v, regs, 1);
- instruction_done(regs, eip, 0);
+ instruction_done(regs, eip);
return EXCRET_fault_fixed;
}
@@ -1378,7 +1375,7 @@ static int emulate_forced_invalid_op(str
pv_cpuid(regs);
- instruction_done(regs, eip, 0);
+ instruction_done(regs, eip);
trace_trap_one_addr(TRC_PV_FORCED_INVALID_OP, regs->eip);
@@ -2023,6 +2020,155 @@ static int read_gate_descriptor(unsigned
return 1;
}
+static int pv_emul_virt_to_linear(unsigned long base, unsigned long offset,
+ unsigned int bytes, unsigned long limit,
+ enum x86_segment seg,
+ struct x86_emulate_ctxt *ctxt,
+ unsigned long *addr)
+{
+ int rc = X86EMUL_OKAY;
+
+ *addr = base + offset;
+
+ if ( ctxt->addr_size < 8 )
+ {
+ if ( limit < bytes - 1 || offset > limit - bytes + 1 )
+ rc = X86EMUL_EXCEPTION;
+ *addr = (uint32_t)*addr;
+ }
+ else if ( !__addr_ok(*addr) )
+ rc = X86EMUL_EXCEPTION;
+
+ if ( unlikely(rc == X86EMUL_EXCEPTION) )
+ x86_emul_hw_exception(seg != x86_seg_ss ? TRAP_gp_fault
+ : TRAP_stack_error,
+ 0, ctxt);
+
+ return rc;
+}
+
+struct priv_op_ctxt {
+ struct x86_emulate_ctxt ctxt;
+ struct {
+ unsigned long base, limit;
+ } cs;
+ char *io_emul_stub;
+ unsigned int bpmatch;
+ unsigned int tsc;
+#define TSC_BASE 1
+#define TSC_AUX 2
+};
+
+static int priv_op_insn_fetch(enum x86_segment seg,
+ unsigned long offset,
+ void *p_data,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt)
+{
+ const struct priv_op_ctxt *poc =
+ container_of(ctxt, struct priv_op_ctxt, ctxt);
+ unsigned int rc;
+ unsigned long addr = poc->cs.base + offset;
+
+ ASSERT(seg == x86_seg_cs);
+
+ /* We don't mean to emulate any branches. */
+ if ( !bytes )
+ return X86EMUL_UNHANDLEABLE;
+
+ rc = pv_emul_virt_to_linear(poc->cs.base, offset, bytes, poc->cs.limit,
+ x86_seg_cs, ctxt, &addr);
+ if ( rc != X86EMUL_OKAY )
+ return rc;
+
+ if ( (rc = __copy_from_user(p_data, (void *)addr, bytes)) != 0 )
+ {
+ x86_emul_pagefault(cpu_has_nx ? PFEC_insn_fetch : 0,
+ addr + bytes - rc, ctxt);
+ return X86EMUL_EXCEPTION;
+ }
+
+ return X86EMUL_OKAY;
+}
+
+static int priv_op_read_segment(enum x86_segment seg,
+ struct segment_register *reg,
+ struct x86_emulate_ctxt *ctxt)
+{
+ if ( ctxt->addr_size < 8 )
+ {
+ unsigned long limit;
+ unsigned int sel, ar;
+
+ switch ( seg )
+ {
+ case x86_seg_cs: sel = ctxt->regs->cs; break;
+ case x86_seg_ds: sel = read_sreg(ds); break;
+ case x86_seg_es: sel = read_sreg(es); break;
+ case x86_seg_fs: sel = read_sreg(fs); break;
+ case x86_seg_gs: sel = read_sreg(gs); break;
+ case x86_seg_ss: sel = ctxt->regs->ss; break;
+ case x86_seg_tr:
+ /* Check if this is an attempt to access to I/O bitmap. */
+ if ( (ctxt->opcode & ~0xb) == 0xe4 || (ctxt->opcode & ~3) == 0x6c )
+ return X86EMUL_DONE;
+ /* fall through */
+ default: return X86EMUL_UNHANDLEABLE;
+ }
+
+ if ( !read_descriptor(sel, current, ®->base, &limit, &ar, 0) )
+ return X86EMUL_UNHANDLEABLE;
+
+ reg->limit = limit;
+ reg->attr.bytes = ar >> 8;
+ }
+ else
+ {
+ switch ( seg )
+ {
+ default:
+ if ( !is_x86_user_segment(seg) )
+ return X86EMUL_UNHANDLEABLE;
+ reg->base = 0;
+ break;
+ case x86_seg_fs:
+ reg->base = rdfsbase();
+ break;
+ case x86_seg_gs:
+ reg->base = rdgsbase();
+ break;
+ }
+
+ reg->limit = ~0U;
+
+ reg->attr.bytes = 0;
+ reg->attr.fields.type = _SEGMENT_WR >> 8;
+ if ( seg == x86_seg_cs )
+ {
+ reg->attr.fields.type |= _SEGMENT_CODE >> 8;
+ reg->attr.fields.l = 1;
+ }
+ else
+ reg->attr.fields.db = 1;
+ reg->attr.fields.s = 1;
+ reg->attr.fields.dpl = 3;
+ reg->attr.fields.p = 1;
+ reg->attr.fields.g = 1;
+ }
+
+ /*
+ * For x86_emulate.c's mode_ring0() to work, fake a DPL of zero.
+ * Also do this for consistency for non-conforming code segments.
+ */
+ if ( (seg == x86_seg_ss ||
+ (seg == x86_seg_cs &&
+ !(reg->attr.fields.type & (_SEGMENT_EC >> 8)))) &&
+ guest_kernel_mode(current, ctxt->regs) )
+ reg->attr.fields.dpl = 0;
+
+ return X86EMUL_OKAY;
+}
+
/* Perform IOPL check between the vcpu's shadowed IOPL, and the assumed cpl. */
static bool_t iopl_ok(const struct vcpu *v, const struct cpu_user_regs *regs)
{
@@ -2269,6 +2415,238 @@ unsigned long guest_to_host_gpr_switch(u
void (*pv_post_outb_hook)(unsigned int port, u8 value);
+typedef void io_emul_stub_t(struct cpu_user_regs *);
+
+static io_emul_stub_t *io_emul_stub_setup(struct priv_op_ctxt *ctxt, u8 opcode,
+ unsigned int port, unsigned int
bytes)
+{
+ if ( !ctxt->io_emul_stub )
+ ctxt->io_emul_stub = map_domain_page(_mfn(this_cpu(stubs.mfn))) +
+ (this_cpu(stubs.addr) &
+ ~PAGE_MASK) +
+ STUB_BUF_SIZE / 2;
+
+ /* movq $host_to_guest_gpr_switch,%rcx */
+ ctxt->io_emul_stub[0] = 0x48;
+ ctxt->io_emul_stub[1] = 0xb9;
+ *(void **)&ctxt->io_emul_stub[2] = (void *)host_to_guest_gpr_switch;
+ /* callq *%rcx */
+ ctxt->io_emul_stub[10] = 0xff;
+ ctxt->io_emul_stub[11] = 0xd1;
+ /* data16 or nop */
+ ctxt->io_emul_stub[12] = (bytes != 2) ? 0x90 : 0x66;
+ /* <io-access opcode> */
+ ctxt->io_emul_stub[13] = opcode;
+ /* imm8 or nop */
+ ctxt->io_emul_stub[14] = !(opcode & 8) ? port : 0x90;
+ /* ret (jumps to guest_to_host_gpr_switch) */
+ ctxt->io_emul_stub[15] = 0xc3;
+ BUILD_BUG_ON(STUB_BUF_SIZE / 2 < 16);
+
+ if ( ioemul_handle_quirk )
+ ioemul_handle_quirk(opcode, &ctxt->io_emul_stub[12], ctxt->ctxt.regs);
+
+ /* Handy function-typed pointer to the stub. */
+ return (void *)(this_cpu(stubs.addr) + STUB_BUF_SIZE / 2);
+}
+
+static int priv_op_read_io(unsigned int port, unsigned int bytes,
+ unsigned long *val, struct x86_emulate_ctxt *ctxt)
+{
+ struct priv_op_ctxt *poc = container_of(ctxt, struct priv_op_ctxt, ctxt);
+ struct vcpu *curr = current;
+ struct domain *currd = current->domain;
+
+ /* INS must not come here. */
+ ASSERT((ctxt->opcode & ~9) == 0xe4);
+
+ if ( !guest_io_okay(port, bytes, curr, ctxt->regs) )
+ return X86EMUL_UNHANDLEABLE;
+
+ poc->bpmatch = check_guest_io_breakpoint(curr, port, bytes);
+
+ if ( admin_io_okay(port, bytes, currd) )
+ {
+ io_emul_stub_t *io_emul =
+ io_emul_stub_setup(poc, ctxt->opcode, port, bytes);
+
+ mark_regs_dirty(ctxt->regs);
+ io_emul(ctxt->regs);
+ return X86EMUL_DONE;
+ }
+
+ *val = guest_io_read(port, bytes, currd);
+
+ return X86EMUL_OKAY;
+}
+
+static int priv_op_write_io(unsigned int port, unsigned int bytes,
+ unsigned long val, struct x86_emulate_ctxt *ctxt)
+{
+ struct priv_op_ctxt *poc = container_of(ctxt, struct priv_op_ctxt, ctxt);
+ struct vcpu *curr = current;
+ struct domain *currd = current->domain;
+
+ /* OUTS must not come here. */
+ ASSERT((ctxt->opcode & ~9) == 0xe6);
+
+ if ( !guest_io_okay(port, bytes, curr, ctxt->regs) )
+ return X86EMUL_UNHANDLEABLE;
+
+ poc->bpmatch = check_guest_io_breakpoint(curr, port, bytes);
+
+ if ( admin_io_okay(port, bytes, currd) )
+ {
+ io_emul_stub_t *io_emul =
+ io_emul_stub_setup(poc, ctxt->opcode, port, bytes);
+
+ mark_regs_dirty(ctxt->regs);
+ io_emul(ctxt->regs);
+ if ( (bytes == 1) && pv_post_outb_hook )
+ pv_post_outb_hook(port, val);
+ return X86EMUL_DONE;
+ }
+
+ guest_io_write(port, bytes, val, currd);
+
+ return X86EMUL_OKAY;
+}
+
+static int priv_op_rep_ins(uint16_t port,
+ enum x86_segment seg, unsigned long offset,
+ unsigned int bytes_per_rep, unsigned long *reps,
+ struct x86_emulate_ctxt *ctxt)
+{
+ struct priv_op_ctxt *poc = container_of(ctxt, struct priv_op_ctxt, ctxt);
+ struct vcpu *curr = current;
+ struct domain *currd = current->domain;
+ unsigned long goal = *reps;
+ struct segment_register sreg;
+ int rc;
+
+ ASSERT(seg == x86_seg_es);
+
+ *reps = 0;
+
+ if ( !guest_io_okay(port, bytes_per_rep, curr, ctxt->regs) )
+ return X86EMUL_UNHANDLEABLE;
+
+ rc = priv_op_read_segment(x86_seg_es, &sreg, ctxt);
+ if ( rc != X86EMUL_OKAY )
+ return rc;
+
+ if ( !sreg.attr.fields.p )
+ return X86EMUL_UNHANDLEABLE;
+ if ( !sreg.attr.fields.s ||
+ (sreg.attr.fields.type & (_SEGMENT_CODE >> 8)) ||
+ !(sreg.attr.fields.type & (_SEGMENT_WR >> 8)) )
+ {
+ x86_emul_hw_exception(TRAP_gp_fault, 0, ctxt);
+ return X86EMUL_EXCEPTION;
+ }
+
+ poc->bpmatch = check_guest_io_breakpoint(curr, port, bytes_per_rep);
+
+ while ( *reps < goal )
+ {
+ unsigned int data = guest_io_read(port, bytes_per_rep, currd);
+ unsigned long addr;
+
+ rc = pv_emul_virt_to_linear(sreg.base, offset, bytes_per_rep,
+ sreg.limit, x86_seg_es, ctxt, &addr);
+ if ( rc != X86EMUL_OKAY )
+ return rc;
+
+ if ( (rc = __copy_to_user((void *)addr, &data, bytes_per_rep)) != 0 )
+ {
+ x86_emul_pagefault(PFEC_write_access,
+ addr + bytes_per_rep - rc, ctxt);
+ return X86EMUL_EXCEPTION;
+ }
+
+ ++*reps;
+
+ if ( poc->bpmatch || hypercall_preempt_check() )
+ break;
+
+ /* x86_emulate() clips the repetition count to ensure we don't wrap. */
+ if ( unlikely(ctxt->regs->_eflags & X86_EFLAGS_DF) )
+ offset -= bytes_per_rep;
+ else
+ offset += bytes_per_rep;
+ }
+
+ return X86EMUL_OKAY;
+}
+
+static int priv_op_rep_outs(enum x86_segment seg, unsigned long offset,
+ uint16_t port,
+ unsigned int bytes_per_rep, unsigned long *reps,
+ struct x86_emulate_ctxt *ctxt)
+{
+ struct priv_op_ctxt *poc = container_of(ctxt, struct priv_op_ctxt, ctxt);
+ struct vcpu *curr = current;
+ struct domain *currd = current->domain;
+ unsigned long goal = *reps;
+ struct segment_register sreg;
+ int rc;
+
+ *reps = 0;
+
+ if ( !guest_io_okay(port, bytes_per_rep, curr, ctxt->regs) )
+ return X86EMUL_UNHANDLEABLE;
+
+ rc = priv_op_read_segment(seg, &sreg, ctxt);
+ if ( rc != X86EMUL_OKAY )
+ return rc;
+
+ if ( !sreg.attr.fields.p )
+ return X86EMUL_UNHANDLEABLE;
+ if ( !sreg.attr.fields.s ||
+ ((sreg.attr.fields.type & (_SEGMENT_CODE >> 8)) &&
+ !(sreg.attr.fields.type & (_SEGMENT_WR >> 8))) )
+ {
+ x86_emul_hw_exception(seg != x86_seg_ss ? TRAP_gp_fault
+ : TRAP_stack_error,
+ 0, ctxt);
+ return X86EMUL_EXCEPTION;
+ }
+
+ poc->bpmatch = check_guest_io_breakpoint(curr, port, bytes_per_rep);
+
+ while ( *reps < goal )
+ {
+ unsigned int data = 0;
+ unsigned long addr;
+
+ rc = pv_emul_virt_to_linear(sreg.base, offset, bytes_per_rep,
+ sreg.limit, seg, ctxt, &addr);
+ if ( rc != X86EMUL_OKAY )
+ return rc;
+
+ if ( (rc = __copy_from_user(&data, (void *)addr, bytes_per_rep)) != 0 )
+ {
+ x86_emul_pagefault(0, addr + bytes_per_rep - rc, ctxt);
+ return X86EMUL_EXCEPTION;
+ }
+
+ guest_io_write(port, bytes_per_rep, data, currd);
+
+ ++*reps;
+
+ if ( poc->bpmatch || hypercall_preempt_check() )
+ break;
+
+ /* x86_emulate() clips the repetition count to ensure we don't wrap. */
+ if ( unlikely(ctxt->regs->_eflags & X86_EFLAGS_DF) )
+ offset -= bytes_per_rep;
+ else
+ offset += bytes_per_rep;
+ }
+
+ return X86EMUL_OKAY;
+}
+
static int priv_op_read_cr(unsigned int reg, unsigned long *val,
struct x86_emulate_ctxt *ctxt)
{
@@ -2409,6 +2787,7 @@ static inline bool is_cpufreq_controller
static int priv_op_read_msr(unsigned int reg, uint64_t *val,
struct x86_emulate_ctxt *ctxt)
{
+ struct priv_op_ctxt *poc = container_of(ctxt, struct priv_op_ctxt, ctxt);
const struct vcpu *curr = current;
const struct domain *currd = curr->domain;
bool vpmu_msr = false;
@@ -2436,6 +2815,28 @@ static int priv_op_read_msr(unsigned int
*val = curr->arch.pv_vcpu.gs_base_user;
return X86EMUL_OKAY;
+ /*
+ * In order to fully retain original behavior, defer calling
+ * pv_soft_rdtsc() until after emulation. This may want/need to be
+ * reconsidered.
+ */
+ case MSR_IA32_TSC:
+ poc->tsc |= TSC_BASE;
+ goto normal;
+
+ case MSR_TSC_AUX:
+ poc->tsc |= TSC_AUX;
+ if ( cpu_has_rdtscp )
+ goto normal;
+ *val = 0;
+ return X86EMUL_OKAY;
+
+ case MSR_EFER:
+ *val = read_efer();
+ if ( is_pv_32bit_domain(currd) )
+ *val &= ~(EFER_LME | EFER_LMA | EFER_LMSLE);
+ return X86EMUL_OKAY;
+
case MSR_K7_FID_VID_CTL:
case MSR_K7_FID_VID_STATUS:
case MSR_K8_PSTATE_LIMIT:
@@ -2539,7 +2940,6 @@ static int priv_op_read_msr(unsigned int
if ( rc )
return X86EMUL_OKAY;
/* fall through */
- case MSR_EFER:
normal:
/* Everyone can read the MSR space. */
/* gdprintk(XENLOG_WARNING, "Domain attempted RDMSR %08x\n", reg); */
@@ -2761,11 +3161,41 @@ static int priv_op_write_msr(unsigned in
return X86EMUL_UNHANDLEABLE;
}
+static int priv_op_wbinvd(struct x86_emulate_ctxt *ctxt)
+{
+ /* Ignore the instruction if unprivileged. */
+ if ( !cache_flush_permitted(current->domain) )
+ /*
+ * Non-physdev domain attempted WBINVD; ignore for now since
+ * newer linux uses this in some start-of-day timing loops.
+ */
+ ;
+ else
+ wbinvd();
+
+ return X86EMUL_OKAY;
+}
+
int pv_emul_cpuid(unsigned int *eax, unsigned int *ebx, unsigned int *ecx,
unsigned int *edx, struct x86_emulate_ctxt *ctxt)
{
struct cpu_user_regs regs = *ctxt->regs;
+ /*
+ * x86_emulate uses this function to query CPU features for its own
+ * internal use. Make sure we're actually emulating CPUID before checking
+ * for emulated CPUID faulting.
+ */
+ if ( ctxt->opcode == X86EMUL_OPC(0x0f, 0xa2) )
+ {
+ const struct vcpu *curr = current;
+
+ /* If cpuid faulting is enabled and CPL>0 leave the #GP untouched. */
+ if ( curr->arch.cpuid_faulting &&
+ !guest_kernel_mode(curr, ctxt->regs) )
+ return X86EMUL_EXCEPTION;
+ }
+
regs._eax = *eax;
regs._ecx = *ecx;
@@ -2779,497 +3209,153 @@ int pv_emul_cpuid(unsigned int *eax, uns
return X86EMUL_OKAY;
}
-/* Instruction fetch with error handling. */
-#define insn_fetch(type, base, eip, limit) \
-({ unsigned long _rc, _ptr = (base) + (eip); \
- type _x; \
- if ( ad_default < 8 ) \
- _ptr = (unsigned int)_ptr; \
- if ( (limit) < sizeof(_x) - 1 || (eip) > (limit) - (sizeof(_x) - 1) ) \
- goto fail; \
- if ( (_rc = copy_from_user(&_x, (type *)_ptr, sizeof(_x))) != 0 ) \
- { \
- pv_inject_page_fault(0, _ptr + sizeof(_x) - _rc); \
- goto skip; \
- } \
- (eip) += sizeof(_x); _x; })
-
-static int emulate_privileged_op(struct cpu_user_regs *regs)
+static int priv_op_validate(const struct x86_emulate_state *state,
+ struct x86_emulate_ctxt *ctxt)
{
- struct vcpu *v = current;
- struct domain *currd = v->domain;
- unsigned long *reg, eip = regs->eip;
- u8 opcode, modrm_reg = 0, modrm_rm = 0, rep_prefix = 0, lock = 0, rex = 0;
- enum { lm_seg_none, lm_seg_fs, lm_seg_gs } lm_ovr = lm_seg_none;
- int rc;
- unsigned int port, i, data_sel, ar, data, bpmatch = 0;
- unsigned int op_bytes, op_default, ad_bytes, ad_default, opsize_prefix= 0;
-#define rd_ad(reg) (ad_bytes >= sizeof(regs->reg) \
- ? regs->reg \
- : ad_bytes == 4 \
- ? (u32)regs->reg \
- : (u16)regs->reg)
-#define wr_ad(reg, val) (ad_bytes >= sizeof(regs->reg) \
- ? regs->reg = (val) \
- : ad_bytes == 4 \
- ? (*(u32 *)®s->reg = (val)) \
- : (*(u16 *)®s->reg = (val)))
- unsigned long code_base, code_limit;
- char *io_emul_stub = NULL;
- void (*io_emul)(struct cpu_user_regs *);
- uint64_t val;
-
- if ( !read_descriptor(regs->cs, v, &code_base, &code_limit, &ar, 1) )
- goto fail;
- op_default = op_bytes = (ar & (_SEGMENT_L|_SEGMENT_DB)) ? 4 : 2;
- ad_default = ad_bytes = (ar & _SEGMENT_L) ? 8 : op_default;
- if ( !(ar & _SEGMENT_S) ||
- !(ar & _SEGMENT_P) ||
- !(ar & _SEGMENT_CODE) )
- goto fail;
-
- /* emulating only opcodes not allowing SS to be default */
- data_sel = read_sreg(ds);
-
- /* Legacy prefixes. */
- for ( i = 0; i < 8; i++, rex == opcode || (rex = 0) )
+ switch ( ctxt->opcode )
{
- switch ( opcode = insn_fetch(u8, code_base, eip, code_limit) )
- {
- case 0x66: /* operand-size override */
- opsize_prefix = 1;
- op_bytes = op_default ^ 6; /* switch between 2/4 bytes */
- continue;
- case 0x67: /* address-size override */
- ad_bytes = ad_default != 4 ? 4 : 2; /* switch to 2/4 bytes */
- continue;
- case 0x2e: /* CS override */
- data_sel = regs->cs;
- continue;
- case 0x3e: /* DS override */
- data_sel = read_sreg(ds);
- continue;
- case 0x26: /* ES override */
- data_sel = read_sreg(es);
- continue;
- case 0x64: /* FS override */
- data_sel = read_sreg(fs);
- lm_ovr = lm_seg_fs;
- continue;
- case 0x65: /* GS override */
- data_sel = read_sreg(gs);
- lm_ovr = lm_seg_gs;
- continue;
- case 0x36: /* SS override */
- data_sel = regs->ss;
- continue;
- case 0xf0: /* LOCK */
- lock = 1;
- continue;
- case 0xf2: /* REPNE/REPNZ */
- case 0xf3: /* REP/REPE/REPZ */
- rep_prefix = 1;
- continue;
- default:
- if ( (ar & _SEGMENT_L) && (opcode & 0xf0) == 0x40 )
- {
- rex = opcode;
- continue;
- }
- break;
- }
- break;
- }
-
- /* REX prefix. */
- if ( rex & 8 ) /* REX.W */
- op_bytes = 4; /* emulate only opcodes not supporting 64-bit operands */
- modrm_reg = (rex & 4) << 1; /* REX.R */
- /* REX.X does not need to be decoded. */
- modrm_rm = (rex & 1) << 3; /* REX.B */
-
- if ( opcode == 0x0f )
- goto twobyte_opcode;
-
- if ( lock )
- goto fail;
-
- /* Input/Output String instructions. */
- if ( (opcode >= 0x6c) && (opcode <= 0x6f) )
- {
- unsigned long data_base, data_limit;
-
- if ( rep_prefix && (rd_ad(ecx) == 0) )
- goto done;
-
- if ( !(opcode & 2) )
- {
- data_sel = read_sreg(es);
- lm_ovr = lm_seg_none;
- }
-
- if ( !(ar & _SEGMENT_L) )
- {
- if ( !read_descriptor(data_sel, v, &data_base, &data_limit,
- &ar, 0) )
- goto fail;
- if ( !(ar & _SEGMENT_S) ||
- !(ar & _SEGMENT_P) ||
- (opcode & 2 ?
- (ar & _SEGMENT_CODE) && !(ar & _SEGMENT_WR) :
- (ar & _SEGMENT_CODE) || !(ar & _SEGMENT_WR)) )
- goto fail;
- }
- else
- {
- switch ( lm_ovr )
- {
- default:
- data_base = 0UL;
- break;
- case lm_seg_fs:
- data_base = rdfsbase();
- break;
- case lm_seg_gs:
- data_base = rdgsbase();
- break;
- }
- data_limit = ~0UL;
- ar = _SEGMENT_WR|_SEGMENT_S|_SEGMENT_DPL|_SEGMENT_P;
- }
-
- port = (u16)regs->edx;
+ case 0x6c ... 0x6f: /* ins / outs */
+ case 0xe4 ... 0xe7: /* in / out (immediate port) */
+ case 0xec ... 0xef: /* in / out (port in %dx) */
+ case X86EMUL_OPC(0x0f, 0x06): /* clts */
+ case X86EMUL_OPC(0x0f, 0x09): /* wbinvd */
+ case X86EMUL_OPC(0x0f, 0x20) ...
+ X86EMUL_OPC(0x0f, 0x23): /* mov to/from cr/dr */
+ case X86EMUL_OPC(0x0f, 0x30): /* wrmsr */
+ case X86EMUL_OPC(0x0f, 0x31): /* rdtsc */
+ case X86EMUL_OPC(0x0f, 0x32): /* rdmsr */
+ case X86EMUL_OPC(0x0f, 0xa2): /* cpuid */
+ return X86EMUL_OKAY;
- continue_io_string:
- switch ( opcode )
- {
- case 0x6c: /* INSB */
- op_bytes = 1;
- case 0x6d: /* INSW/INSL */
- if ( (data_limit < (op_bytes - 1)) ||
- (rd_ad(edi) > (data_limit - (op_bytes - 1))) ||
- !guest_io_okay(port, op_bytes, v, regs) )
- goto fail;
- data = guest_io_read(port, op_bytes, currd);
- if ( (rc = copy_to_user((void *)data_base + rd_ad(edi),
- &data, op_bytes)) != 0 )
- {
- pv_inject_page_fault(PFEC_write_access,
- data_base + rd_ad(edi) + op_bytes - rc);
- return EXCRET_fault_fixed;
- }
- wr_ad(edi, regs->edi + (int)((regs->eflags & X86_EFLAGS_DF)
- ? -op_bytes : op_bytes));
+ case 0xfa: case 0xfb: /* cli / sti */
+ if ( !iopl_ok(current, ctxt->regs) )
break;
-
- case 0x6e: /* OUTSB */
- op_bytes = 1;
- case 0x6f: /* OUTSW/OUTSL */
- if ( (data_limit < (op_bytes - 1)) ||
- (rd_ad(esi) > (data_limit - (op_bytes - 1))) ||
- !guest_io_okay(port, op_bytes, v, regs) )
- goto fail;
- if ( (rc = copy_from_user(&data, (void *)data_base + rd_ad(esi),
- op_bytes)) != 0 )
- {
- pv_inject_page_fault(0, data_base + rd_ad(esi)
- + op_bytes - rc);
- return EXCRET_fault_fixed;
- }
- guest_io_write(port, op_bytes, data, currd);
- wr_ad(esi, regs->esi + (int)((regs->eflags & X86_EFLAGS_DF)
- ? -op_bytes : op_bytes));
- break;
- }
-
- bpmatch = check_guest_io_breakpoint(v, port, op_bytes);
-
- if ( rep_prefix && (wr_ad(ecx, regs->ecx - 1) != 0) )
- {
- if ( !bpmatch && !hypercall_preempt_check() )
- goto continue_io_string;
- eip = regs->eip;
- }
-
- goto done;
- }
-
- /*
- * Very likely to be an I/O instruction (IN/OUT).
- * Build an stub to execute the instruction with full guest GPR
- * context. This is needed for some systems which (ab)use IN/OUT
- * to communicate with BIOS code in system-management mode.
- */
- io_emul_stub = map_domain_page(_mfn(this_cpu(stubs.mfn))) +
- (this_cpu(stubs.addr) & ~PAGE_MASK) +
- STUB_BUF_SIZE / 2;
- /* movq $host_to_guest_gpr_switch,%rcx */
- io_emul_stub[0] = 0x48;
- io_emul_stub[1] = 0xb9;
- *(void **)&io_emul_stub[2] = (void *)host_to_guest_gpr_switch;
- /* callq *%rcx */
- io_emul_stub[10] = 0xff;
- io_emul_stub[11] = 0xd1;
- /* data16 or nop */
- io_emul_stub[12] = (op_bytes != 2) ? 0x90 : 0x66;
- /* <io-access opcode> */
- io_emul_stub[13] = opcode;
- /* imm8 or nop */
- io_emul_stub[14] = 0x90;
- /* ret (jumps to guest_to_host_gpr_switch) */
- io_emul_stub[15] = 0xc3;
- BUILD_BUG_ON(STUB_BUF_SIZE / 2 < 16);
-
- /* Handy function-typed pointer to the stub. */
- io_emul = (void *)(this_cpu(stubs.addr) + STUB_BUF_SIZE / 2);
-
- if ( ioemul_handle_quirk )
- ioemul_handle_quirk(opcode, &io_emul_stub[12], regs);
-
- /* I/O Port and Interrupt Flag instructions. */
- switch ( opcode )
- {
- case 0xe4: /* IN imm8,%al */
- op_bytes = 1;
- case 0xe5: /* IN imm8,%eax */
- port = insn_fetch(u8, code_base, eip, code_limit);
- io_emul_stub[14] = port; /* imm8 */
- exec_in:
- if ( !guest_io_okay(port, op_bytes, v, regs) )
- goto fail;
- if ( admin_io_okay(port, op_bytes, currd) )
- {
- mark_regs_dirty(regs);
- io_emul(regs);
- }
- else
- {
- if ( op_bytes == 4 )
- regs->eax = 0;
- else
- regs->eax &= ~((1 << (op_bytes * 8)) - 1);
- regs->eax |= guest_io_read(port, op_bytes, currd);
- }
- bpmatch = check_guest_io_breakpoint(v, port, op_bytes);
- goto done;
-
- case 0xec: /* IN %dx,%al */
- op_bytes = 1;
- case 0xed: /* IN %dx,%eax */
- port = (u16)regs->edx;
- goto exec_in;
-
- case 0xe6: /* OUT %al,imm8 */
- op_bytes = 1;
- case 0xe7: /* OUT %eax,imm8 */
- port = insn_fetch(u8, code_base, eip, code_limit);
- io_emul_stub[14] = port; /* imm8 */
- exec_out:
- if ( !guest_io_okay(port, op_bytes, v, regs) )
- goto fail;
- if ( admin_io_okay(port, op_bytes, currd) )
- {
- mark_regs_dirty(regs);
- io_emul(regs);
- if ( (op_bytes == 1) && pv_post_outb_hook )
- pv_post_outb_hook(port, regs->eax);
- }
- else
- {
- guest_io_write(port, op_bytes, regs->eax, currd);
- }
- bpmatch = check_guest_io_breakpoint(v, port, op_bytes);
- goto done;
-
- case 0xee: /* OUT %al,%dx */
- op_bytes = 1;
- case 0xef: /* OUT %eax,%dx */
- port = (u16)regs->edx;
- goto exec_out;
-
- case 0xfa: /* CLI */
- case 0xfb: /* STI */
- if ( !iopl_ok(v, regs) )
- goto fail;
/*
* This is just too dangerous to allow, in my opinion. Consider if the
* caller then tries to reenable interrupts using POPF: we can't trap
* that and we'll end up with hard-to-debug lockups. Fast & loose will
* do for us. :-)
+ vcpu_info(current, evtchn_upcall_mask) = (ctxt->opcode == 0xfa);
*/
- /*v->vcpu_info->evtchn_upcall_mask = (opcode == 0xfa);*/
- goto done;
- }
+ return X86EMUL_DONE;
- /* No decode of this single-byte opcode. */
- goto fail;
+ case X86EMUL_OPC(0x0f, 0x01):
+ {
+ unsigned int modrm_rm, modrm_reg;
- twobyte_opcode:
- /*
- * All 2 and 3 byte opcodes, except RDTSC (0x31), RDTSCP (0x1,0xF9),
- * and CPUID (0xa2), are executable only from guest kernel mode
- * (virtual ring 0).
- */
- opcode = insn_fetch(u8, code_base, eip, code_limit);
- if ( !guest_kernel_mode(v, regs) &&
- (opcode != 0x1) && (opcode != 0x31) && (opcode != 0xa2) )
- goto fail;
-
- if ( lock && (opcode & ~3) != 0x20 )
- goto fail;
- switch ( opcode )
- {
- case 0x1: /* RDTSCP and XSETBV */
- switch ( insn_fetch(u8, code_base, eip, code_limit) )
- {
- case 0xf9: /* RDTSCP */
- if ( (v->arch.pv_vcpu.ctrlreg[4] & X86_CR4_TSD) &&
- !guest_kernel_mode(v, regs) )
- goto fail;
- pv_soft_rdtsc(v, regs, 1);
+ if ( x86_insn_modrm(state, &modrm_rm, &modrm_reg) != 3 ||
+ (modrm_rm & 7) != 1 )
break;
- case 0xd1: /* XSETBV */
+ switch ( modrm_reg & 7 )
{
- u64 new_xfeature = (u32)regs->eax | ((u64)regs->edx << 32);
+ case 2: /* xsetbv */
+ case 7: /* rdtscp */
+ return X86EMUL_OKAY;
+ }
+ break;
+ }
+ }
- if ( lock || rep_prefix || opsize_prefix
- || !(v->arch.pv_vcpu.ctrlreg[4] & X86_CR4_OSXSAVE) )
- {
- do_guest_trap(TRAP_invalid_op, regs);
- goto skip;
- }
+ return X86EMUL_UNHANDLEABLE;
+}
- if ( !guest_kernel_mode(v, regs) )
- goto fail;
+static const struct x86_emulate_ops priv_op_ops = {
+ .insn_fetch = priv_op_insn_fetch,
+ .read = x86emul_unhandleable_rw,
+ .validate = priv_op_validate,
+ .read_io = priv_op_read_io,
+ .write_io = priv_op_write_io,
+ .rep_ins = priv_op_rep_ins,
+ .rep_outs = priv_op_rep_outs,
+ .read_segment = priv_op_read_segment,
+ .read_cr = priv_op_read_cr,
+ .write_cr = priv_op_write_cr,
+ .read_dr = priv_op_read_dr,
+ .write_dr = priv_op_write_dr,
+ .read_msr = priv_op_read_msr,
+ .write_msr = priv_op_write_msr,
+ .cpuid = pv_emul_cpuid,
+ .wbinvd = priv_op_wbinvd,
+};
- if ( handle_xsetbv(regs->ecx, new_xfeature) )
- goto fail;
+static int emulate_privileged_op(struct cpu_user_regs *regs)
+{
+ struct vcpu *curr = current;
+ struct domain *currd = curr->domain;
+ struct priv_op_ctxt ctxt = { .ctxt.regs = regs };
+ int rc;
+ unsigned int eflags, ar;
- break;
- }
- default:
- goto fail;
- }
- break;
+ if ( !read_descriptor(regs->cs, curr, &ctxt.cs.base, &ctxt.cs.limit,
+ &ar, 1) ||
+ !(ar & _SEGMENT_S) ||
+ !(ar & _SEGMENT_P) ||
+ !(ar & _SEGMENT_CODE) )
+ return 0;
- case 0x06: /* CLTS */
- (void)do_fpu_taskswitch(0);
- break;
+ /* Mirror virtualized state into EFLAGS. */
+ ASSERT(regs->_eflags & X86_EFLAGS_IF);
+ if ( vcpu_info(curr, evtchn_upcall_mask) )
+ regs->_eflags &= ~X86_EFLAGS_IF;
+ else
+ regs->_eflags |= X86_EFLAGS_IF;
+ ASSERT(!(regs->_eflags & X86_EFLAGS_IOPL));
+ regs->_eflags |= curr->arch.pv_vcpu.iopl;
+ eflags = regs->_eflags;
+
+ ctxt.ctxt.addr_size = ar & _SEGMENT_L ? 64 : ar & _SEGMENT_DB ? 32 : 16;
+ /* Leave zero in ctxt.ctxt.sp_size, as it's not needed. */
+ rc = x86_emulate(&ctxt.ctxt, &priv_op_ops);
- case 0x09: /* WBINVD */
- /* Ignore the instruction if unprivileged. */
- if ( !cache_flush_permitted(currd) )
- /* Non-physdev domain attempted WBINVD; ignore for now since
- newer linux uses this in some start-of-day timing loops */
- ;
- else
- wbinvd();
- break;
+ if ( ctxt.io_emul_stub )
+ unmap_domain_page(ctxt.io_emul_stub);
- case 0x20: /* MOV CR?,<reg> */
- opcode = insn_fetch(u8, code_base, eip, code_limit);
- if ( opcode < 0xc0 )
- goto fail;
- modrm_reg += ((opcode >> 3) & 7) + (lock << 3);
- modrm_rm |= (opcode >> 0) & 7;
- if ( priv_op_read_cr(modrm_reg, decode_register(modrm_rm, regs, 0),
- NULL) != X86EMUL_OKAY )
- goto fail;
- break;
-
- case 0x21: /* MOV DR?,<reg> */ {
- opcode = insn_fetch(u8, code_base, eip, code_limit);
- if ( opcode < 0xc0 )
- goto fail;
- modrm_reg += ((opcode >> 3) & 7) + (lock << 3);
- modrm_rm |= (opcode >> 0) & 7;
- if ( priv_op_read_dr(modrm_reg, decode_register(modrm_rm, regs, 0),
- NULL) != X86EMUL_OKAY )
- goto fail;
- break;
- }
+ /*
+ * Un-mirror virtualized state from EFLAGS.
+ * Nothing we allow to be emulated can change TF, IF, or IOPL.
+ */
+ ASSERT(!((regs->_eflags ^ eflags) & (X86_EFLAGS_IF | X86_EFLAGS_IOPL)));
+ regs->_eflags |= X86_EFLAGS_IF;
+ regs->_eflags &= ~X86_EFLAGS_IOPL;
+
+ /* More strict than x86_emulate_wrapper(). */
+ ASSERT(ctxt.ctxt.event_pending == (rc == X86EMUL_EXCEPTION));
+
+ switch ( rc )
+ {
+ case X86EMUL_OKAY:
+ if ( ctxt.tsc & TSC_BASE )
+ {
+ if ( ctxt.tsc & TSC_AUX )
+ pv_soft_rdtsc(curr, regs, 1);
+ else if ( currd->arch.vtsc )
+ pv_soft_rdtsc(curr, regs, 0);
+ else
+ {
+ uint64_t val = rdtsc();
- case 0x22: /* MOV <reg>,CR? */
- opcode = insn_fetch(u8, code_base, eip, code_limit);
- if ( opcode < 0xc0 )
- goto fail;
- modrm_reg += ((opcode >> 3) & 7) + (lock << 3);
- modrm_rm |= (opcode >> 0) & 7;
- reg = decode_register(modrm_rm, regs, 0);
- switch ( priv_op_write_cr(modrm_reg, *reg, NULL) )
- {
- case X86EMUL_OKAY:
- break;
- case X86EMUL_RETRY: /* retry after preemption */
- goto skip;
- default:
- goto fail;
+ regs->eax = (uint32_t)val;
+ regs->edx = (uint32_t)(val >> 32);
+ }
}
- break;
-
- case 0x23: /* MOV <reg>,DR? */
- opcode = insn_fetch(u8, code_base, eip, code_limit);
- if ( opcode < 0xc0 )
- goto fail;
- modrm_reg += ((opcode >> 3) & 7) + (lock << 3);
- modrm_rm |= (opcode >> 0) & 7;
- reg = decode_register(modrm_rm, regs, 0);
- if ( priv_op_write_dr(modrm_reg, *reg, NULL) != X86EMUL_OKAY )
- goto fail;
- break;
- case 0x30: /* WRMSR */
- if ( priv_op_write_msr(regs->_ecx, (regs->rdx << 32) | regs->_eax,
- NULL) != X86EMUL_OKAY )
- goto fail;
- break;
-
- case 0x31: /* RDTSC */
- if ( (v->arch.pv_vcpu.ctrlreg[4] & X86_CR4_TSD) &&
- !guest_kernel_mode(v, regs) )
- goto fail;
- if ( currd->arch.vtsc )
- pv_soft_rdtsc(v, regs, 0);
- else
+ if ( ctxt.ctxt.retire.singlestep )
+ ctxt.bpmatch |= DR_STEP;
+ if ( ctxt.bpmatch )
{
- val = rdtsc();
- goto rdmsr_writeback;
+ curr->arch.debugreg[6] |= ctxt.bpmatch | DR_STATUS_RESERVED_ONE;
+ if ( !(curr->arch.pv_vcpu.trap_bounce.flags & TBF_EXCEPTION) )
+ do_guest_trap(TRAP_debug, regs);
}
- break;
-
- case 0x32: /* RDMSR */
- if ( priv_op_read_msr(regs->_ecx, &val, NULL) != X86EMUL_OKAY )
- goto fail;
- rdmsr_writeback:
- regs->eax = (uint32_t)val;
- regs->edx = (uint32_t)(val >> 32);
- break;
-
- case 0xa2: /* CPUID */
- /* If cpuid faulting is enabled and CPL>0 leave the #GP untouched. */
- if ( v->arch.cpuid_faulting && !guest_kernel_mode(v, regs) )
- goto fail;
-
- pv_cpuid(regs);
- break;
+ /* fall through */
+ case X86EMUL_RETRY:
+ return EXCRET_fault_fixed;
- default:
- goto fail;
+ case X86EMUL_EXCEPTION:
+ pv_inject_event(&ctxt.ctxt.event);
+ return EXCRET_fault_fixed;
}
-#undef wr_ad
-#undef rd_ad
-
- done:
- instruction_done(regs, eip, bpmatch);
- skip:
- if ( io_emul_stub )
- unmap_domain_page(io_emul_stub);
- return EXCRET_fault_fixed;
-
- fail:
- if ( io_emul_stub )
- unmap_domain_page(io_emul_stub);
return 0;
}
@@ -3615,7 +3702,7 @@ static void emulate_gate_op(struct cpu_u
sel |= (regs->cs & 3);
regs->cs = sel;
- instruction_done(regs, off, 0);
+ instruction_done(regs, off);
}
void do_general_protection(struct cpu_user_regs *regs)
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1185,7 +1185,7 @@ static int ioport_access_check(
fail_if(ops->read_segment == NULL);
if ( (rc = ops->read_segment(x86_seg_tr, &tr, ctxt)) != 0 )
- return rc;
+ return rc == X86EMUL_DONE ? X86EMUL_OKAY : rc;
/* Ensure the TSS has an io-bitmap-offset field. */
generate_exception_if(tr.attr.fields.type != 0xb, EXC_GP, 0);
@@ -2506,6 +2506,21 @@ x86_emulate(
/* Sync rIP to post decode value. */
_regs.eip = state.eip;
+ if ( ops->validate )
+ {
+#ifndef NDEBUG
+ state.caller = __builtin_return_address(0);
+#endif
+ rc = ops->validate(&state, ctxt);
+#ifndef NDEBUG
+ state.caller = NULL;
+#endif
+ if ( rc == X86EMUL_DONE )
+ goto no_writeback;
+ if ( rc != X86EMUL_OKAY )
+ return rc;
+ }
+
b = ctxt->opcode;
d = state.desc;
#define state (&state)
@@ -2935,13 +2950,28 @@ x86_emulate(
dst.mem.off = truncate_ea_and_reps(_regs.edi, nr_reps, dst.bytes);
if ( (rc = ioport_access_check(port, dst.bytes, ctxt, ops)) != 0 )
goto done;
- if ( (nr_reps == 1) || !ops->rep_ins ||
- ((rc = ops->rep_ins(port, dst.mem.seg, dst.mem.off, dst.bytes,
- &nr_reps, ctxt)) == X86EMUL_UNHANDLEABLE) )
+ /* Try the presumably most efficient approach first. */
+ if ( !ops->rep_ins )
+ nr_reps = 1;
+ rc = X86EMUL_UNHANDLEABLE;
+ if ( nr_reps == 1 && ops->read_io && ops->write )
{
- fail_if(ops->read_io == NULL);
+ rc = ops->read_io(port, dst.bytes, &dst.val, ctxt);
+ if ( rc == X86EMUL_OKAY )
+ nr_reps = 0;
+ }
+ if ( (nr_reps > 1 || rc == X86EMUL_UNHANDLEABLE) && ops->rep_ins )
+ rc = ops->rep_ins(port, dst.mem.seg, dst.mem.off, dst.bytes,
+ &nr_reps, ctxt);
+ if ( nr_reps >= 1 && rc == X86EMUL_UNHANDLEABLE )
+ {
+ fail_if(!ops->read_io || !ops->write);
if ( (rc = ops->read_io(port, dst.bytes, &dst.val, ctxt)) != 0 )
goto done;
+ nr_reps = 0;
+ }
+ if ( !nr_reps && rc == X86EMUL_OKAY )
+ {
dst.type = OP_MEM;
nr_reps = 1;
}
@@ -2959,14 +2989,30 @@ x86_emulate(
ea.mem.off = truncate_ea_and_reps(_regs.esi, nr_reps, dst.bytes);
if ( (rc = ioport_access_check(port, dst.bytes, ctxt, ops)) != 0 )
goto done;
- if ( (nr_reps == 1) || !ops->rep_outs ||
- ((rc = ops->rep_outs(ea.mem.seg, ea.mem.off, port, dst.bytes,
- &nr_reps, ctxt)) == X86EMUL_UNHANDLEABLE) )
+ /* Try the presumably most efficient approach first. */
+ if ( !ops->rep_outs )
+ nr_reps = 1;
+ rc = X86EMUL_UNHANDLEABLE;
+ if ( nr_reps == 1 && ops->write_io )
{
- if ( (rc = read_ulong(ea.mem.seg, truncate_ea(_regs.esi),
- &dst.val, dst.bytes, ctxt, ops)) != 0 )
+ rc = read_ulong(ea.mem.seg, ea.mem.off, &dst.val, dst.bytes,
+ ctxt, ops);
+ if ( rc == X86EMUL_OKAY )
+ nr_reps = 0;
+ }
+ if ( (nr_reps > 1 || rc == X86EMUL_UNHANDLEABLE) && ops->rep_outs )
+ rc = ops->rep_outs(ea.mem.seg, ea.mem.off, port, dst.bytes,
+ &nr_reps, ctxt);
+ if ( nr_reps >= 1 && rc == X86EMUL_UNHANDLEABLE )
+ {
+ if ( (rc = read_ulong(ea.mem.seg, ea.mem.off, &dst.val,
+ dst.bytes, ctxt, ops)) != X86EMUL_OKAY )
goto done;
fail_if(ops->write_io == NULL);
+ nr_reps = 0;
+ }
+ if ( !nr_reps && rc == X86EMUL_OKAY )
+ {
if ( (rc = ops->write_io(port, dst.bytes, dst.val, ctxt)) != 0 )
goto done;
nr_reps = 1;
@@ -4039,7 +4085,11 @@ x86_emulate(
rc = ops->read_io(port, dst.bytes, &dst.val, ctxt);
}
if ( rc != 0 )
+ {
+ if ( rc == X86EMUL_DONE )
+ goto no_writeback;
goto done;
+ }
break;
}
@@ -5445,9 +5495,7 @@ x86_emulate(
break;
}
- no_writeback:
- /* Commit shadow register state. */
- _regs.eflags &= ~EFLG_RF;
+ no_writeback: /* Commit shadow register state. */
/* Zero the upper 32 bits of %rip if not in 64-bit mode. */
if ( !mode_64bit() )
@@ -5457,7 +5505,15 @@ x86_emulate(
if ( (rc == X86EMUL_OKAY) && (ctxt->regs->eflags & EFLG_TF) )
ctxt->retire.singlestep = true;
- *ctxt->regs = _regs;
+ if ( rc != X86EMUL_DONE )
+ *ctxt->regs = _regs;
+ else
+ {
+ ctxt->regs->eip = _regs.eip;
+ rc = X86EMUL_OKAY;
+ }
+
+ ctxt->regs->eflags &= ~EFLG_RF;
done:
_put_fpu();
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -146,6 +146,14 @@ struct __attribute__((__packed__)) segme
#define X86EMUL_EXCEPTION 2
/* Retry the emulation for some reason. No state modified. */
#define X86EMUL_RETRY 3
+ /*
+ * Operation fully done by one of the hooks:
+ * - validate(): operation completed (except common insn retire logic)
+ * - read_segment(x86_seg_tr, ...): bypass I/O bitmap access
+ * - read_io() / write_io(): bypass GPR update (non-string insns only)
+ * Undefined behavior when used anywhere else.
+ */
+#define X86EMUL_DONE 4
/* FPU sub-types which may be requested via ->get_fpu(). */
enum x86_emulate_fpu_type {
@@ -156,6 +164,8 @@ enum x86_emulate_fpu_type {
X86EMUL_FPU_ymm /* AVX/XOP instruction set (%ymm0-%ymm7/15) */
};
+struct x86_emulate_state;
+
/*
* These operations represent the instruction emulator's interface to memory,
* I/O ports, privileged state... pretty much everything other than GPRs.
@@ -238,6 +248,14 @@ struct x86_emulate_ops
struct x86_emulate_ctxt *ctxt);
/*
+ * validate: Post-decode, pre-emulate hook to allow caller controlled
+ * filtering.
+ */
+ int (*validate)(
+ const struct x86_emulate_state *state,
+ struct x86_emulate_ctxt *ctxt);
+
+ /*
* rep_ins: Emulate INS: <src_port> -> <dst_seg:dst_offset>.
* @bytes_per_rep: [IN ] Bytes transferred per repetition.
* @reps: [IN ] Maximum repetitions to be emulated.
Attachment:
x86-PV-priv-op-generic-emul.patch _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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