FAILED: patch "[PATCH] KVM: nVMX: Defer the MMU reload to the normal path on an EPTP" failed to apply to 5.4-stable tree

FAILED: patch "[PATCH] KVM: nVMX: Defer the MMU reload to the normal path on an EPTP" failed to apply to 5.4-stable tree

[gregkh]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c805f5d5585ab5e0cdac6b1ccf7086eb120fb7db Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Thu, 4 Mar 2021 17:10:57 -0800
Subject: [PATCH] KVM: nVMX: Defer the MMU reload to the normal path on an EPTP
 switch

Defer reloading the MMU after a EPTP successful EPTP switch.  The VMFUNC
instruction itself is executed in the previous EPTP context, any side
effects, e.g. updating RIP, should occur in the old context.  Practically
speaking, this bug is benign as VMX doesn't touch the MMU when skipping
an emulated instruction, nor does queuing a single-step #DB.  No other
post-switch side effects exist.

Fixes: 41ab93727467 ("KVM: nVMX: Emulate EPTP switching for the L1 hypervisor")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index bd1343a0896e..d74abd778429 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5481,16 +5481,11 @@ static int nested_vmx_eptp_switching(struct kvm_vcpu *vcpu,
 		if (!nested_vmx_check_eptp(vcpu, new_eptp))
 			return 1;
 
-		kvm_mmu_unload(vcpu);
 		mmu->ept_ad = accessed_dirty;
 		mmu->mmu_role.base.ad_disabled = !accessed_dirty;
 		vmcs12->ept_pointer = new_eptp;
-		/*
-		 * TODO: Check what's the correct approach in case
-		 * mmu reload fails. Currently, we just let the next
-		 * reload potentially fail
-		 */
-		kvm_mmu_reload(vcpu);
+
+		kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu);
 	}
 
 	return 0;