diff options
| author | Sean Christopherson <seanjc@google.com> | 2022-05-26 21:08:14 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-06-10 10:01:31 -0400 |
| commit | b443183a25ab61840a12de92f8822849e017b9c8 (patch) | |
| tree | b3f1773c38494a32c798eb5f93e037c2833938b0 /arch | |
| parent | 0cbc60d44c35b1070eb4070b499164d27d050576 (diff) | |
KVM: x86: Reduce the number of emulator GPRs to '8' for 32-bit KVM
Reduce the number of GPRs emulated by 32-bit KVM from 16 to 8. KVM does
not support emulating 64-bit mode on 32-bit host kernels, and so should
never generate accesses to R8-15.
Opportunistically use NR_EMULATOR_GPRS in rsm_load_state_{32,64}() now
that it is precise and accurate for both flavors.
Wrap the definition with full #ifdef ugliness; sadly, IS_ENABLED()
doesn't guarantee a compile-time constant as far as BUILD_BUG_ON() is
concerned.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Message-Id: <20220526210817.3428868-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/emulate.c | 4 | ||||
| -rw-r--r-- | arch/x86/kvm/kvm_emulate.h | 7 |
2 files changed, 6 insertions, 5 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 5aaf1d1200af..77161f57c8d3 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -2441,7 +2441,7 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt, ctxt->eflags = GET_SMSTATE(u32, smstate, 0x7ff4) | X86_EFLAGS_FIXED; ctxt->_eip = GET_SMSTATE(u32, smstate, 0x7ff0); - for (i = 0; i < 8; i++) + for (i = 0; i < NR_EMULATOR_GPRS; i++) *reg_write(ctxt, i) = GET_SMSTATE(u32, smstate, 0x7fd0 + i * 4); val = GET_SMSTATE(u32, smstate, 0x7fcc); @@ -2498,7 +2498,7 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt, u16 selector; int i, r; - for (i = 0; i < 16; i++) + for (i = 0; i < NR_EMULATOR_GPRS; i++) *reg_write(ctxt, i) = GET_SMSTATE(u64, smstate, 0x7ff8 - i * 8); ctxt->_eip = GET_SMSTATE(u64, smstate, 0x7f78); diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h index 3a65d6ea7fe6..034c845b3c63 100644 --- a/arch/x86/kvm/kvm_emulate.h +++ b/arch/x86/kvm/kvm_emulate.h @@ -306,11 +306,12 @@ typedef void (*fastop_t)(struct fastop *); * tracked/accessed via _eip, and except for RIP relative addressing, which * also uses _eip, RIP cannot be a register operand nor can it be an operand in * a ModRM or SIB byte. - * - * TODO: this is technically wrong for 32-bit KVM, which only supports 8 GPRs; - * R8-R15 don't exist. */ +#ifdef CONFIG_X86_64 #define NR_EMULATOR_GPRS 16 +#else +#define NR_EMULATOR_GPRS 8 +#endif struct x86_emulate_ctxt { void *vcpu; |