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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2/3] x86/hvm: Improvements to external users of decode_register()
* Rename to decode_gpr() to be more specific as to its purpose
* Drop the highbyte encoding handling, as users care, and it unlikely that
future users would care.
* Change to a static inline, returning an unsigned long pointer.
Doing so highlights that the "invalid gpr" paths in hvm_mov_{to,from}_cr()
were actually unreachable. All callers already passed in-range gprs, which
would have hit a BUG() previously.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
Future work: We should have gpr_{read,write}() helpers which suitably
cast/truncate values, because all these callsites have broken corner cases,
but that involves wiring the current operand size thought, which I haven't got
time to do right now.
---
xen/arch/x86/hvm/hvm.c | 17 ++---------------
xen/arch/x86/hvm/vmx/vvmx.c | 16 +++-------------
xen/arch/x86/x86_emulate/x86_emulate.c | 2 +-
xen/arch/x86/x86_emulate/x86_emulate.h | 25 +++++++++++++++++++++----
4 files changed, 27 insertions(+), 33 deletions(-)
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 2689046..59ef754 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2059,16 +2059,9 @@ static void hvm_set_uc_mode(struct vcpu *v, bool_t
is_in_uc_mode)
int hvm_mov_to_cr(unsigned int cr, unsigned int gpr)
{
struct vcpu *curr = current;
- unsigned long val, *reg;
+ unsigned long val = *decode_gpr(guest_cpu_user_regs(), gpr);
int rc;
- if ( (reg = decode_register(gpr, guest_cpu_user_regs(), 0)) == NULL )
- {
- gdprintk(XENLOG_ERR, "invalid gpr: %u\n", gpr);
- goto exit_and_crash;
- }
-
- val = *reg;
HVMTRACE_LONG_2D(CR_WRITE, cr, TRC_PAR_LONG(val));
HVM_DBG_LOG(DBG_LEVEL_1, "CR%u, value = %lx", cr, val);
@@ -2109,13 +2102,7 @@ int hvm_mov_to_cr(unsigned int cr, unsigned int gpr)
int hvm_mov_from_cr(unsigned int cr, unsigned int gpr)
{
struct vcpu *curr = current;
- unsigned long val = 0, *reg;
-
- if ( (reg = decode_register(gpr, guest_cpu_user_regs(), 0)) == NULL )
- {
- gdprintk(XENLOG_ERR, "invalid gpr: %u\n", gpr);
- goto exit_and_crash;
- }
+ unsigned long val = 0, *reg = decode_gpr(guest_cpu_user_regs(), gpr);
switch ( cr )
{
diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index 885eab3..dfe97b9 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -347,18 +347,14 @@ enum vmx_insn_errno set_vvmcs_real_safe(const struct vcpu
*v, u32 encoding,
static unsigned long reg_read(struct cpu_user_regs *regs,
unsigned int index)
{
- unsigned long *pval = decode_register(index, regs, 0);
-
- return *pval;
+ return *decode_gpr(regs, index);
}
static void reg_write(struct cpu_user_regs *regs,
unsigned int index,
unsigned long value)
{
- unsigned long *pval = decode_register(index, regs, 0);
-
- *pval = value;
+ *decode_gpr(regs, index) = value;
}
static inline u32 __n2_pin_exec_control(struct vcpu *v)
@@ -2483,14 +2479,8 @@ int nvmx_n2_vmexit_handler(struct cpu_user_regs *regs,
case VMX_CONTROL_REG_ACCESS_TYPE_MOV_TO_CR:
{
unsigned long gp =
VMX_CONTROL_REG_ACCESS_GPR(exit_qualification);
- unsigned long *reg;
+ val = *decode_gpr(guest_cpu_user_regs(), gp);
- if ( (reg = decode_register(gp, guest_cpu_user_regs(), 0)) ==
NULL )
- {
- gdprintk(XENLOG_ERR, "invalid gpr: %lx\n", gp);
- break;
- }
- val = *reg;
if ( cr == 0 )
{
u64 cr0_gh_mask = get_vvmcs(v, CR0_GUEST_HOST_MASK);
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 3f5636f..70c38a2 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -400,7 +400,7 @@ static const uint8_t pmov_convert_delta[] = { 1, 2, 3, 1,
2, 1 };
* Map GPRs by ModRM encoding to their offset within struct cpu_user_regs.
* The AH,CH,DH,BH offsets are misaligned.
*/
-static const uint8_t cpu_user_regs_gpr_offsets[] = {
+const uint8_t cpu_user_regs_gpr_offsets[] = {
offsetof(struct cpu_user_regs, r(ax)),
offsetof(struct cpu_user_regs, r(cx)),
offsetof(struct cpu_user_regs, r(dx)),
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.h
b/xen/arch/x86/x86_emulate/x86_emulate.h
index 0c8c80a..5cdcfdd 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -25,6 +25,14 @@
#define MAX_INST_LEN 15
+#if defined(__i386__)
+# define X86_NR_GPRS 8
+#elif defined(__x86_64__)
+# define X86_NR_GPRS 16
+#else
+# error Unknown compilation width
+#endif
+
struct x86_emulate_ctxt;
/*
@@ -601,14 +609,23 @@ int x86_emulate_wrapper(
#define x86_emulate x86_emulate_wrapper
#endif
+/* Map GPRs by ModRM encoding to their offset within struct cpu_user_regs. */
+extern const uint8_t cpu_user_regs_gpr_offsets[X86_NR_GPRS];
+
/*
* Given the 'reg' portion of a ModRM byte, and a register block, return a
* pointer into the block that addresses the relevant register.
- * @highbyte_regs specifies whether to decode AH,CH,DH,BH.
*/
-void *
-decode_register(
- uint8_t modrm_reg, struct cpu_user_regs *regs, int highbyte_regs);
+static inline unsigned long *decode_gpr(struct cpu_user_regs *regs,
+ unsigned int modrm)
+{
+ ASSERT(modrm < ARRAY_SIZE(cpu_user_regs_gpr_offsets));
+
+ /* For safety in release builds. Debug builds will hit the ASSERT() */
+ modrm &= ARRAY_SIZE(cpu_user_regs_gpr_offsets) - 1;
+
+ return (void *)regs + cpu_user_regs_gpr_offsets[modrm];
+}
/* Unhandleable read, write or instruction fetch */
int
--
2.1.4
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