FAILED: patch "[PATCH] KVM: x86: Check CR3 GPA for validity regardless of vCPU mode" failed to apply to 4.4-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.4-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 886bbcc7a523b8d4fac60f1015d2e0fcad50db82 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Wed, 21 Apr 2021 19:21:21 -0700
Subject: [PATCH] KVM: x86: Check CR3 GPA for validity regardless of vCPU mode

Check CR3 for an invalid GPA even if the vCPU isn't in long mode.  For
bigger emulation flows, notably RSM, the vCPU mode may not be accurate
if CR0/CR4 are loaded after CR3.  For MOV CR3 and similar flows, the
caller is responsible for truncating the value.

Fixes: 660a5d517aaa ("KVM: x86: save/load state on SMM switch")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210422022128.3464144-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4c9c9592a437..3010284dc59b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1077,10 +1077,15 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
 		return 0;
 	}
 
-	if (is_long_mode(vcpu) && kvm_vcpu_is_illegal_gpa(vcpu, cr3))
+	/*
+	 * Do not condition the GPA check on long mode, this helper is used to
+	 * stuff CR3, e.g. for RSM emulation, and there is no guarantee that
+	 * the current vCPU mode is accurate.
+	 */
+	if (kvm_vcpu_is_illegal_gpa(vcpu, cr3))
 		return 1;
-	else if (is_pae_paging(vcpu) &&
-		 !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
+
+	if (is_pae_paging(vcpu) && !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
 		return 1;
 
 	kvm_mmu_new_pgd(vcpu, cr3, skip_tlb_flush, skip_tlb_flush);