diff options
Diffstat (limited to 'arch/x86/kvm/emulate.c')
| -rw-r--r-- | arch/x86/kvm/emulate.c | 45 |
1 files changed, 9 insertions, 36 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 5d4c86133453..1fb73d96bdf0 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -2363,41 +2363,6 @@ static bool vendor_intel(struct x86_emulate_ctxt *ctxt) return is_guest_vendor_intel(ebx, ecx, edx); } -static bool em_syscall_is_enabled(struct x86_emulate_ctxt *ctxt) -{ - const struct x86_emulate_ops *ops = ctxt->ops; - u32 eax, ebx, ecx, edx; - - /* - * syscall should always be enabled in longmode - so only become - * vendor specific (cpuid) if other modes are active... - */ - if (ctxt->mode == X86EMUL_MODE_PROT64) - return true; - - eax = 0x00000000; - ecx = 0x00000000; - ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, true); - /* - * remark: Intel CPUs only support "syscall" in 64bit longmode. Also a - * 64bit guest with a 32bit compat-app running will #UD !! While this - * behaviour can be fixed (by emulating) into AMD response - CPUs of - * AMD can't behave like Intel. - */ - if (is_guest_vendor_intel(ebx, ecx, edx)) - return false; - - if (is_guest_vendor_amd(ebx, ecx, edx) || - is_guest_vendor_hygon(ebx, ecx, edx)) - return true; - - /* - * default: (not Intel, not AMD, not Hygon), apply Intel's - * stricter rules... - */ - return false; -} - static int em_syscall(struct x86_emulate_ctxt *ctxt) { const struct x86_emulate_ops *ops = ctxt->ops; @@ -2411,7 +2376,15 @@ static int em_syscall(struct x86_emulate_ctxt *ctxt) ctxt->mode == X86EMUL_MODE_VM86) return emulate_ud(ctxt); - if (!(em_syscall_is_enabled(ctxt))) + /* + * Intel compatible CPUs only support SYSCALL in 64-bit mode, whereas + * AMD allows SYSCALL in any flavor of protected mode. Note, it's + * infeasible to emulate Intel behavior when running on AMD hardware, + * as SYSCALL won't fault in the "wrong" mode, i.e. there is no #UD + * for KVM to trap-and-emulate, unlike emulating AMD on Intel. + */ + if (ctxt->mode != X86EMUL_MODE_PROT64 && + ctxt->ops->guest_cpuid_is_intel_compatible(ctxt)) return emulate_ud(ctxt); ops->get_msr(ctxt, MSR_EFER, &efer); |