[Devel] [PATCH] Revert "KVM: nested VMX: disable perf cpuid reporting"

[Denis Plotnikov]

From: Jim Mattson <jmattson at google.com>

This reverts commit bc6134942dbbf31c25e9bd7c876be5da81c9e1ce.

A CPUID instruction executed in VMX non-root mode always causes a
VM-exit, regardless of the leaf being queried.

Fixes: bc6134942dbb ("KVM: nested VMX: disable perf cpuid reporting")
Signed-off-by: Jim Mattson <jmattson at google.com>
[The issue solved by bc6134942dbb has been resolved with ff651cb613b4
 ("KVM: nVMX: Add nested msr load/restore algorithm").]
Signed-off-by: Radim Krčmář <rkrcmar at redhat.com>

(cherry picked from commit 0b4c208d443ba2af82b4c70f99ca8df31e9a0020)

fix #PSBM-68274

Signed-off-by: Denis Plotnikov <dplotnikov at virtuozzo.com>
---
 arch/x86/kvm/cpuid.c | 6 ------
 arch/x86/kvm/vmx.c   | 2 --
 2 files changed, 8 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index e245bf66..f6be926 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -831,12 +831,6 @@ void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
 	if (!best)
 		best = check_cpuid_limit(vcpu, function, index);
 
-	/*
-	 * Perfmon not yet supported for L2 guest.
-	 */
-	if (is_guest_mode(vcpu) && function == 0xa)
-		best = NULL;
-
 	if (best) {
 		*eax = best->eax;
 		*ebx = best->ebx;
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 16ca8fa..6fd1049 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7663,8 +7663,6 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
 	case EXIT_REASON_TASK_SWITCH:
 		return true;
 	case EXIT_REASON_CPUID:
-		if (kvm_register_read(vcpu, VCPU_REGS_RAX) == 0xa)
-			return false;
 		return true;
 	case EXIT_REASON_HLT:
 		return nested_cpu_has(vmcs12, CPU_BASED_HLT_EXITING);
-- 
2.7.4