* FAILED: patch "[PATCH] KVM: x86: Clear KVM's cached guest CR3 at RESET/INIT" failed to apply to 4.14-stable tree
@ 2021-10-03 14:10 gregkh
0 siblings, 0 replies; only message in thread
From: gregkh @ 2021-10-03 14:10 UTC (permalink / raw)
To: seanjc, pbonzini; +Cc: stable
The patch below does not apply to the 4.14-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 03a6e84069d1870f5b3d360e64cb330b66f76dee Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Mon, 20 Sep 2021 17:02:55 -0700
Subject: [PATCH] KVM: x86: Clear KVM's cached guest CR3 at RESET/INIT
Explicitly zero the guest's CR3 and mark it available+dirty at RESET/INIT.
Per Intel's SDM and AMD's APM, CR3 is zeroed at both RESET and INIT. For
RESET, this is a nop as vcpu is zero-allocated. For INIT, the bug has
likely escaped notice because no firmware/kernel puts its page tables root
at PA=0, let alone relies on INIT to get the desired CR3 for such page
tables.
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210921000303.400537-3-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 06026f3d7ea2..8a83dd1b882e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10895,6 +10895,9 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
kvm_set_rflags(vcpu, X86_EFLAGS_FIXED);
kvm_rip_write(vcpu, 0xfff0);
+ vcpu->arch.cr3 = 0;
+ kvm_register_mark_dirty(vcpu, VCPU_EXREG_CR3);
+
/*
* CR0.CD/NW are set on RESET, preserved on INIT. Note, some versions
* of Intel's SDM list CD/NW as being set on INIT, but they contradict
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2021-10-03 14:10 FAILED: patch "[PATCH] KVM: x86: Clear KVM's cached guest CR3 at RESET/INIT" failed to apply to 4.14-stable tree gregkh
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