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Subject[PATCH v4] KVM: emulate: Don't inject #GP when emulating RDMPC if CR0.PE=0
Date
From: Wanpeng Li <wanpengli@tencent.com>

SDM mentioned that we should #GP for rdpmc if ECX is not valid or
(CR4.PCE is 0 and CPL is 1, 2, or 3 and CR0.PE is 1).

Let's add the CR0.PE is 1 checking to rdpmc emulate, though this isn't
strictly necessary since it's impossible for CPL to be >0 if CR0.PE=0.

Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
v3 -> v4:
* add comments instead of pseudocode
v2 -> v3:
* add the missing 'S'
v1 -> v2:
* update patch description

arch/x86/kvm/emulate.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 9a144ca8e146..ab7ec569e8c9 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -4213,6 +4213,7 @@ static int check_rdtsc(struct x86_emulate_ctxt *ctxt)
static int check_rdpmc(struct x86_emulate_ctxt *ctxt)
{
u64 cr4 = ctxt->ops->get_cr(ctxt, 4);
+ u64 cr0 = ctxt->ops->get_cr(ctxt, 0);
u64 rcx = reg_read(ctxt, VCPU_REGS_RCX);

/*
@@ -4222,7 +4223,7 @@ static int check_rdpmc(struct x86_emulate_ctxt *ctxt)
if (enable_vmware_backdoor && is_vmware_backdoor_pmc(rcx))
return X86EMUL_CONTINUE;

- if ((!(cr4 & X86_CR4_PCE) && ctxt->ops->cpl(ctxt)) ||
+ if ((!(cr4 & X86_CR4_PCE) && ctxt->ops->cpl(ctxt) && (cr0 & X86_CR0_PE)) ||
ctxt->ops->check_pmc(ctxt, rcx))
return emulate_gp(ctxt, 0);

--
2.25.1
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