From: Will Deacon <will@kernel.org>
To: kvmarm@lists.cs.columbia.edu, maz@kernel.org
Cc: kernel-team@android.com, stable@vger.kernel.org,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH] KVM: arm64: Avoid corrupting vCPU context register in guest exit
Date: Fri, 26 Feb 2021 18:12:11 +0000 [thread overview]
Message-ID: <20210226181211.14542-1-will@kernel.org> (raw)
Commit 7db21530479f ("KVM: arm64: Restore hyp when panicking in guest
context") tracks the currently running vCPU, clearing the pointer to
NULL on exit from a guest.
Unfortunately, the use of 'set_loaded_vcpu' clobbers x1 to point at the
kvm_hyp_ctxt instead of the vCPU context, causing the subsequent RAS
code to go off into the weeds when it saves the DISR assuming that the
CPU context is embedded in a struct vCPU.
Leave x1 alone and use x3 as a temporary register instead when clearing
the vCPU on the guest exit path.
Cc: Marc Zyngier <maz@kernel.org>
Cc: Andrew Scull <ascull@google.com>
Cc: <stable@vger.kernel.org>
Fixes: 7db21530479f ("KVM: arm64: Restore hyp when panicking in guest context")
Suggested-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
This was pretty awful to debug!
arch/arm64/kvm/hyp/entry.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index b0afad7a99c6..0c66a1d408fd 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -146,7 +146,7 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
// Now restore the hyp regs
restore_callee_saved_regs x2
- set_loaded_vcpu xzr, x1, x2
+ set_loaded_vcpu xzr, x2, x3
alternative_if ARM64_HAS_RAS_EXTN
// If we have the RAS extensions we can consume a pending error
--
2.30.1.766.gb4fecdf3b7-goog
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next reply other threads:[~2021-02-26 18:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 18:12 Will Deacon [this message]
2021-02-26 18:35 ` [PATCH] KVM: arm64: Avoid corrupting vCPU context register in guest exit Marc Zyngier
2021-02-26 19:05 ` Will Deacon
2021-03-02 18:57 ` Marc Zyngier
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