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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 13/24] PVH xen: Support privileged op emulation for PVH
This patch changes mostly traps.c to support privileged op emulation for PVH.
A new function read_descriptor_sel() is introduced to read descriptor for PVH
given a selector. Another new function vmx_read_selector() reads a selector
from VMCS, to support read_segment_register() for PVH.
Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
---
xen/arch/x86/hvm/vmx/vmx.c | 40 +++++++++++++++++++
xen/arch/x86/traps.c | 86 +++++++++++++++++++++++++++++++++++-----
xen/include/asm-x86/hvm/hvm.h | 7 +++
xen/include/asm-x86/system.h | 19 +++++++--
4 files changed, 137 insertions(+), 15 deletions(-)
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index faf8b46..9be321d 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -664,6 +664,45 @@ static void vmx_ctxt_switch_to(struct vcpu *v)
.fields = { .type = 0xb, .s = 0, .dpl = 0, .p = 1, .avl = 0, \
.l = 0, .db = 0, .g = 0, .pad = 0 } }).bytes)
+u16 vmx_read_selector(struct vcpu *v, enum x86_segment seg)
+{
+ u16 sel = 0;
+
+ vmx_vmcs_enter(v);
+ switch ( seg )
+ {
+ case x86_seg_cs:
+ sel = __vmread(GUEST_CS_SELECTOR);
+ break;
+
+ case x86_seg_ss:
+ sel = __vmread(GUEST_SS_SELECTOR);
+ break;
+
+ case x86_seg_es:
+ sel = __vmread(GUEST_ES_SELECTOR);
+ break;
+
+ case x86_seg_ds:
+ sel = __vmread(GUEST_DS_SELECTOR);
+ break;
+
+ case x86_seg_fs:
+ sel = __vmread(GUEST_FS_SELECTOR);
+ break;
+
+ case x86_seg_gs:
+ sel = __vmread(GUEST_GS_SELECTOR);
+ break;
+
+ default:
+ BUG();
+ }
+ vmx_vmcs_exit(v);
+
+ return sel;
+}
+
void vmx_get_segment_register(struct vcpu *v, enum x86_segment seg,
struct segment_register *reg)
{
@@ -1559,6 +1598,7 @@ static struct hvm_function_table __initdata
vmx_function_table = {
.sync_pir_to_irr = vmx_sync_pir_to_irr,
.nhvm_hap_walk_L1_p2m = nvmx_hap_walk_L1_p2m,
.pvh_set_vcpu_info = vmx_pvh_set_vcpu_info,
+ .read_selector = vmx_read_selector,
};
const struct hvm_function_table * __init start_vmx(void)
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index a3ca70b..fe8b94c 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -480,6 +480,10 @@ static unsigned int check_guest_io_breakpoint(struct vcpu
*v,
unsigned int width, i, match = 0;
unsigned long start;
+ /* PVH fixme: support io breakpoint. */
+ if ( is_pvh_vcpu(v) )
+ return 0;
+
if ( !(v->arch.debugreg[5]) ||
!(v->arch.pv_vcpu.ctrlreg[4] & X86_CR4_DE) )
return 0;
@@ -1525,6 +1529,49 @@ static int read_descriptor(unsigned int sel,
return 1;
}
+static int read_descriptor_sel(unsigned int sel,
+ enum x86_segment which_sel,
+ struct vcpu *v,
+ const struct cpu_user_regs *regs,
+ unsigned long *base,
+ unsigned long *limit,
+ unsigned int *ar,
+ unsigned int vm86attr)
+{
+ struct segment_register seg;
+ bool_t long_mode;
+
+ if ( !is_pvh_vcpu(v) )
+ return read_descriptor(sel, v, regs, base, limit, ar, vm86attr);
+
+ hvm_get_segment_register(v, x86_seg_cs, &seg);
+ long_mode = seg.attr.fields.l;
+
+ if ( which_sel != x86_seg_cs )
+ hvm_get_segment_register(v, which_sel, &seg);
+
+ /* "ar" is returned packed as in segment_attributes_t. Fix it up. */
+ *ar = seg.attr.bytes;
+ *ar = (*ar & 0xff ) | ((*ar & 0xf00) << 4);
+ *ar <<= 8;
+
+ if ( long_mode )
+ {
+ *limit = ~0UL;
+
+ if ( which_sel < x86_seg_fs )
+ {
+ *base = 0UL;
+ return 1;
+ }
+ }
+ else
+ *limit = seg.limit;
+
+ *base = seg.base;
+ return 1;
+}
+
static int read_gate_descriptor(unsigned int gate_sel,
const struct vcpu *v,
unsigned int *sel,
@@ -1590,6 +1637,13 @@ static int guest_io_okay(
int user_mode = !(v->arch.flags & TF_kernel_mode);
#define TOGGLE_MODE() if ( user_mode ) toggle_guest_mode(v)
+ /*
+ * For PVH we check this in vmexit for EXIT_REASON_IO_INSTRUCTION
+ * and so don't need to check again here.
+ */
+ if ( is_pvh_vcpu(v) )
+ return 1;
+
if ( !vm86_mode(regs) &&
(v->arch.pv_vcpu.iopl >= (guest_kernel_mode(v, regs) ? 1 : 3)) )
return 1;
@@ -1835,7 +1889,7 @@ static inline uint64_t guest_misc_enable(uint64_t val)
_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 ) \
+ if ( (_rc = raw_copy_from_guest(&_x, (type *)_ptr, sizeof(_x))) != 0 ) \
{ \
propagate_page_fault(_ptr + sizeof(_x) - _rc, 0); \
goto skip; \
@@ -1852,6 +1906,7 @@ static int is_cpufreq_controller(struct domain *d)
static int emulate_privileged_op(struct cpu_user_regs *regs)
{
+ enum x86_segment which_sel;
struct vcpu *v = current;
unsigned long *reg, eip = regs->eip;
u8 opcode, modrm_reg = 0, modrm_rm = 0, rep_prefix = 0, lock = 0, rex = 0;
@@ -1874,9 +1929,10 @@ static int emulate_privileged_op(struct cpu_user_regs
*regs)
void (*io_emul)(struct cpu_user_regs *) __attribute__((__regparm__(1)));
uint64_t val, msr_content;
- if ( !read_descriptor(regs->cs, v, regs,
- &code_base, &code_limit, &ar,
- _SEGMENT_CODE|_SEGMENT_S|_SEGMENT_DPL|_SEGMENT_P) )
+ if ( !read_descriptor_sel(regs->cs, x86_seg_cs, v, regs,
+ &code_base, &code_limit, &ar,
+ _SEGMENT_CODE|_SEGMENT_S|
+ _SEGMENT_DPL|_SEGMENT_P) )
goto fail;
op_default = op_bytes = (ar & (_SEGMENT_L|_SEGMENT_DB)) ? 4 : 2;
ad_default = ad_bytes = (ar & _SEGMENT_L) ? 8 : op_default;
@@ -1887,6 +1943,7 @@ static int emulate_privileged_op(struct cpu_user_regs
*regs)
/* emulating only opcodes not allowing SS to be default */
data_sel = read_segment_register(v, regs, ds);
+ which_sel = x86_seg_ds;
/* Legacy prefixes. */
for ( i = 0; i < 8; i++, rex == opcode || (rex = 0) )
@@ -1902,23 +1959,29 @@ static int emulate_privileged_op(struct cpu_user_regs
*regs)
continue;
case 0x2e: /* CS override */
data_sel = regs->cs;
+ which_sel = x86_seg_cs;
continue;
case 0x3e: /* DS override */
data_sel = read_segment_register(v, regs, ds);
+ which_sel = x86_seg_ds;
continue;
case 0x26: /* ES override */
data_sel = read_segment_register(v, regs, es);
+ which_sel = x86_seg_es;
continue;
case 0x64: /* FS override */
data_sel = read_segment_register(v, regs, fs);
+ which_sel = x86_seg_fs;
lm_ovr = lm_seg_fs;
continue;
case 0x65: /* GS override */
data_sel = read_segment_register(v, regs, gs);
+ which_sel = x86_seg_gs;
lm_ovr = lm_seg_gs;
continue;
case 0x36: /* SS override */
data_sel = regs->ss;
+ which_sel = x86_seg_ss;
continue;
case 0xf0: /* LOCK */
lock = 1;
@@ -1962,15 +2025,16 @@ static int emulate_privileged_op(struct cpu_user_regs
*regs)
if ( !(opcode & 2) )
{
data_sel = read_segment_register(v, regs, es);
+ which_sel = x86_seg_es;
lm_ovr = lm_seg_none;
}
if ( !(ar & _SEGMENT_L) )
{
- if ( !read_descriptor(data_sel, v, regs,
- &data_base, &data_limit, &ar,
- _SEGMENT_WR|_SEGMENT_S|_SEGMENT_DPL|
- _SEGMENT_P) )
+ if ( !read_descriptor_sel(data_sel, which_sel, v, regs,
+ &data_base, &data_limit, &ar,
+ _SEGMENT_WR|_SEGMENT_S|_SEGMENT_DPL|
+ _SEGMENT_P) )
goto fail;
if ( !(ar & _SEGMENT_S) ||
!(ar & _SEGMENT_P) ||
@@ -2000,9 +2064,9 @@ static int emulate_privileged_op(struct cpu_user_regs
*regs)
}
}
else
- read_descriptor(data_sel, v, regs,
- &data_base, &data_limit, &ar,
- 0);
+ read_descriptor_sel(data_sel, which_sel, v, regs,
+ &data_base, &data_limit, &ar,
+ 0);
data_limit = ~0UL;
ar = _SEGMENT_WR|_SEGMENT_S|_SEGMENT_DPL|_SEGMENT_P;
}
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index aee95f4..51ab230 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -194,6 +194,8 @@ struct hvm_function_table {
bool_t access_w, bool_t access_x);
int (*pvh_set_vcpu_info)(struct vcpu *v, struct vcpu_guest_context *ctxtp);
+
+ u16 (*read_selector)(struct vcpu *v, enum x86_segment seg);
};
extern struct hvm_function_table hvm_funcs;
@@ -333,6 +335,11 @@ static inline int pvh_set_vcpu_info(struct vcpu *v,
return hvm_funcs.pvh_set_vcpu_info(v, ctxtp);
}
+static inline u16 pvh_get_selector(struct vcpu *v, enum x86_segment seg)
+{
+ return hvm_funcs.read_selector(v, seg);
+}
+
#define is_viridian_domain(_d) \
(is_hvm_domain(_d) && ((_d)->arch.hvm_domain.params[HVM_PARAM_VIRIDIAN]))
diff --git a/xen/include/asm-x86/system.h b/xen/include/asm-x86/system.h
index 9bb22cb..1242657 100644
--- a/xen/include/asm-x86/system.h
+++ b/xen/include/asm-x86/system.h
@@ -4,10 +4,21 @@
#include <xen/lib.h>
#include <xen/bitops.h>
-#define read_segment_register(vcpu, regs, name) \
-({ u16 __sel; \
- asm volatile ( "movw %%" STR(name) ",%0" : "=r" (__sel) ); \
- __sel; \
+/*
+ * We need vcpu because during context switch, going from PV to PVH,
+ * in save_segments() current has been updated to next, and no longer pointing
+ * to the PV, but the intention is to get selector for the PV. Checking
+ * is_pvh_vcpu(current) will yield incorrect results in such a case.
+ */
+#define read_segment_register(vcpu, regs, name) \
+({ u16 __sel; \
+ struct cpu_user_regs *_regs = (regs); \
+ \
+ if ( is_pvh_vcpu(vcpu) && guest_mode(_regs) ) \
+ __sel = pvh_get_selector(vcpu, x86_seg_##name); \
+ else \
+ asm volatile ( "movw %%" #name ",%0" : "=r" (__sel) ); \
+ __sel; \
})
#define wbinvd() \
--
1.7.2.3
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