[PATCH RFC v1 09/20] KVM: x86: Support EGPR accessing and tracking for instruction emulation

Chang S. Bae
2025-11-10T18:24:51Z

Extend the emulator context and GPR accessors to handle EGPRs before
adding support for REX2-prefixed instructions.

Now the KVM GPR accessors can handle EGPRs. Then, the emulator can
uniformly cache and track all GPRs without requiring separate handling.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
---
arch/x86/kvm/kvm_emulate.h | 10 +++++-----
arch/x86/kvm/x86.c | 4 ++--
2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index 7b5ddb787a25..153c70ea5561 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -105,13 +105,13 @@ struct x86_instruction_info {
struct x86_emulate_ops {
void (*vm_bugged)(struct x86_emulate_ctxt *ctxt);
/*
- * read_gpr: read a general purpose register (rax - r15)
+ * read_gpr: read a general purpose register (rax - r31)
*
* @reg: gpr number.
*/
ulong (*read_gpr)(struct x86_emulate_ctxt *ctxt, unsigned reg);
/*
- * write_gpr: write a general purpose register (rax - r15)
+ * write_gpr: write a general purpose register (rax - r31)
*
* @reg: gpr number.
* @val: value to write.
@@ -312,7 +312,7 @@ typedef void (*fastop_t)(struct fastop *);
* a ModRM or SIB byte.
*/
#ifdef CONFIG_X86_64
-#define NR_EMULATOR_GPRS 16
+#define NR_EMULATOR_GPRS 32
#else
#define NR_EMULATOR_GPRS 8
#endif
@@ -361,9 +361,9 @@ struct x86_emulate_ctxt {
u8 lock_prefix;
u8 rep_prefix;
/* bitmaps of registers in _regs[] that can be read */
- u16 regs_valid;
+ u32 regs_valid;
/* bitmaps of registers in _regs[] that have been written */
- u16 regs_dirty;
+ u32 regs_dirty;
/* modrm */
u8 modrm;
u8 modrm_mod;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 603057ea7421..338986a5a3ae 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8812,12 +8812,12 @@ static bool emulator_guest_cpuid_is_intel_compatible(struct x86_emulate_ctxt *ct

static ulong emulator_read_gpr(struct x86_emulate_ctxt *ctxt, unsigned reg)
{
- return kvm_register_read_raw(emul_to_vcpu(ctxt), reg);
+ return _kvm_gpr_read(emul_to_vcpu(ctxt), reg);
}

static void emulator_write_gpr(struct x86_emulate_ctxt *ctxt, unsigned reg, ulong val)
{
- kvm_register_write_raw(emul_to_vcpu(ctxt), reg, val);
+ _kvm_gpr_write(emul_to_vcpu(ctxt), reg, val);
}

static void emulator_set_nmi_mask(struct x86_emulate_ctxt *ctxt, bool masked)
--
2.51.0