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From: Will Deacon <will@kernel.org>
To: kvmarm@lists.cs.columbia.edu, maz@kernel.org
Cc: linux-arm-kernel@lists.infradead.org, kernel-team@android.com,
	Will Deacon <will@kernel.org>, Andrew Scull <ascull@google.com>,
	stable@vger.kernel.org, Quentin Perret <qperret@google.com>
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


WARNING: multiple messages have this Message-ID (diff)
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

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org>
To: kvmarm@lists.cs.columbia.edu, maz@kernel.org
Cc: Quentin Perret <qperret@google.com>,
	kernel-team@android.com, stable@vger.kernel.org,
	Andrew Scull <ascull@google.com>, 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


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

             reply	other threads:[~2021-02-26 18:13 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-26 18:12 Will Deacon [this message]
2021-02-26 18:12 ` [PATCH] KVM: arm64: Avoid corrupting vCPU context register in guest exit Will Deacon
2021-02-26 18:12 ` Will Deacon
2021-02-26 18:35 ` Marc Zyngier
2021-02-26 18:35   ` Marc Zyngier
2021-02-26 18:35   ` Marc Zyngier
2021-02-26 19:05   ` Will Deacon
2021-02-26 19:05     ` Will Deacon
2021-02-26 19:05     ` Will Deacon
2021-03-02 18:57 ` Marc Zyngier
2021-03-02 18:57   ` Marc Zyngier
2021-03-02 18:57   ` Marc Zyngier

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