linux-kernel - [PATCH AUTOSEL 4.19 047/237] KVM: nVMX: reset cache/shadows when switching loaded VMCS

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Date:   Sat, 16 Nov 2019 10:38:02 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Jim Mattson <jmattson@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>, kvm@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 047/237] KVM: nVMX: reset cache/shadows when switching loaded VMCS

From: Sean Christopherson <sean.j.christopherson@...el.com>

[ Upstream commit b7031fd40fcc741b0f9b0c04c8d844e445858b84 ]

Reset the vm_{entry,exit}_controls_shadow variables as well as the
segment cache after loading a new VMCS in vmx_switch_vmcs().  The
shadows/cache track VMCS data, i.e. they're stale every time we
switch to a new VMCS regardless of reason.

This fixes a bug where stale control shadows would be consumed after
a nested VMExit due to a failed consistency check.

Suggested-by: Jim Mattson <jmattson@...gle.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Reviewed-by: Jim Mattson <jmattson@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kvm/vmx.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 4eda2a9c234a6..8c7554d7f0a80 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11013,6 +11013,10 @@ static void vmx_switch_vmcs(struct kvm_vcpu *vcpu, struct loaded_vmcs *vmcs)
 	vmx->loaded_vmcs = vmcs;
 	vmx_vcpu_load(vcpu, cpu);
 	put_cpu();
+
+	vm_entry_controls_reset_shadow(vmx);
+	vm_exit_controls_reset_shadow(vmx);
+	vmx_segment_cache_clear(vmx);
 }
 
 /*
@@ -12700,7 +12704,6 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, u32 *exit_qual)
 		vmx->nested.vmcs01_guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS);
 
 	vmx_switch_vmcs(vcpu, &vmx->nested.vmcs02);
-	vmx_segment_cache_clear(vmx);
 
 	if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
 		vcpu->arch.tsc_offset += vmcs12->tsc_offset;
@@ -13531,9 +13534,6 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 	}
 
 	vmx_switch_vmcs(vcpu, &vmx->vmcs01);
-	vm_entry_controls_reset_shadow(vmx);
-	vm_exit_controls_reset_shadow(vmx);
-	vmx_segment_cache_clear(vmx);
 
 	/* Update any VMCS fields that might have changed while L2 ran */
 	vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr);
-- 
2.20.1