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Subject[PATCH v2 2/2] KVM: x86/emulator: Emulate RDPID only if it is enabled in guest
Date
When RDTSCP is supported but RDPID is not supported in host,
RDPID emulation is available. However, __kvm_get_msr() would
only fail when RDTSCP/RDPID both are disabled in guest, so
the emulator wouldn't inject a #UD when RDPID is disabled but
RDTSCP is enabled in guest.

Fixes: fb6d4d340e05 ("KVM: x86: emulate RDPID")
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
arch/x86/kvm/emulate.c | 4 +++-
arch/x86/kvm/kvm_emulate.h | 1 +
arch/x86/kvm/x86.c | 6 ++++++
3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 3497a35bd085..be83c9c8482d 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3521,8 +3521,10 @@ static int em_rdpid(struct x86_emulate_ctxt *ctxt)
{
u64 tsc_aux = 0;

- if (ctxt->ops->get_msr(ctxt, MSR_TSC_AUX, &tsc_aux))
+ if (!ctxt->ops->guest_has_rdpid(ctxt))
return emulate_ud(ctxt);
+
+ ctxt->ops->get_msr(ctxt, MSR_TSC_AUX, &tsc_aux);
ctxt->dst.val = tsc_aux;
return X86EMUL_CONTINUE;
}
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index 29ac5a9679e5..1cbd46cf71f9 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -228,6 +228,7 @@ struct x86_emulate_ops {
bool (*guest_has_long_mode)(struct x86_emulate_ctxt *ctxt);
bool (*guest_has_movbe)(struct x86_emulate_ctxt *ctxt);
bool (*guest_has_fxsr)(struct x86_emulate_ctxt *ctxt);
+ bool (*guest_has_rdpid)(struct x86_emulate_ctxt *ctxt);

void (*set_nmi_mask)(struct x86_emulate_ctxt *ctxt, bool masked);

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 09c5677f4186..44f97038d3e5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7723,6 +7723,11 @@ static bool emulator_guest_has_fxsr(struct x86_emulate_ctxt *ctxt)
return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_FXSR);
}

+static bool emulator_guest_has_rdpid(struct x86_emulate_ctxt *ctxt)
+{
+ return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_RDPID);
+}
+
static ulong emulator_read_gpr(struct x86_emulate_ctxt *ctxt, unsigned reg)
{
return kvm_register_read_raw(emul_to_vcpu(ctxt), reg);
@@ -7807,6 +7812,7 @@ static const struct x86_emulate_ops emulate_ops = {
.guest_has_long_mode = emulator_guest_has_long_mode,
.guest_has_movbe = emulator_guest_has_movbe,
.guest_has_fxsr = emulator_guest_has_fxsr,
+ .guest_has_rdpid = emulator_guest_has_rdpid,
.set_nmi_mask = emulator_set_nmi_mask,
.get_hflags = emulator_get_hflags,
.exiting_smm = emulator_exiting_smm,
--
2.31.1
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