[PATCH v5 4/8] KVM: nVMX: Use kvm_set_msr to load IA32_PERF_GLOBAL_CTRL on VM-Exit

[Oliver Upton <oupton@google.com>]

The existing implementation for loading the IA32_PERF_GLOBAL_CTRL MSR
on VM-exit was incorrect, as the next call to atomic_switch_perf_msrs()
could cause this value to be overwritten. Instead, call kvm_set_msr()
which will allow atomic_switch_perf_msrs() to correctly set the values.

Define a macro, SET_MSR_OR_WARN(), to set the MSR with kvm_set_msr()
and WARN on failure.

Suggested-by: Jim Mattson <jmattson@google.com>
Co-developed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
---
 arch/x86/kvm/vmx/nested.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index f9ae7bc0a421..ecdc706f171b 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -28,6 +28,16 @@ module_param(nested_early_check, bool, S_IRUGO);
 	failed;								\
 })
 
+#define SET_MSR_OR_WARN(vcpu, idx, data)				\
+({									\
+	bool failed = kvm_set_msr(vcpu, idx, data);			\
+	if (failed)							\
+		pr_warn_ratelimited(					\
+				"%s cannot write MSR (0x%x, 0x%llx)\n",	\
+				__func__, idx, data);			\
+	failed;								\
+})
+
 /*
  * Hyper-V requires all of these, so mark them as supported even though
  * they are just treated the same as all-context.
@@ -3867,8 +3877,8 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
 		vcpu->arch.pat = vmcs12->host_ia32_pat;
 	}
 	if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL)
-		vmcs_write64(GUEST_IA32_PERF_GLOBAL_CTRL,
-			vmcs12->host_ia32_perf_global_ctrl);
+		SET_MSR_OR_WARN(vcpu, MSR_CORE_PERF_GLOBAL_CTRL,
+				vmcs12->host_ia32_perf_global_ctrl);
 
 	/* Set L1 segment info according to Intel SDM
 	    27.5.2 Loading Host Segment and Descriptor-Table Registers */
-- 
2.24.0.rc1.363.gb1bccd3e3d-goog