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From: Marc Zyngier <maz@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>,
	Andre Przywara <andre.przywara@arm.com>,
	Andrew Scull <ascull@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Howard Zhang <Howard.Zhang@arm.com>, Jia He <justin.he@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Quentin Perret <qperret@google.com>,
	Shameerali Kolothum Thodi  <shameerali.kolothum.thodi@huawei.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Will Deacon <will@kernel.org>, James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	kernel-team@android.com, linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	stable@vger.kernel.org
Subject: [PATCH 2/8] KVM: arm64: Avoid corrupting vCPU context register in guest exit
Date: Fri,  5 Mar 2021 18:52:48 +0000	[thread overview]
Message-ID: <20210305185254.3730990-3-maz@kernel.org> (raw)
In-Reply-To: <20210305185254.3730990-1-maz@kernel.org>

From: Will Deacon <will@kernel.org>

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>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210226181211.14542-1-will@kernel.org
---
 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
-- 
2.29.2


  parent reply	other threads:[~2021-03-05 18:53 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-05 16:49 [GIT PULL] KVM/arm64 fixes for 5.12, take #1 Marc Zyngier
2021-03-05 17:27 ` Paolo Bonzini
2021-03-05 18:47   ` Marc Zyngier
2021-03-05 18:52     ` [PATCH 0/8] " Marc Zyngier
2021-03-05 18:52       ` [PATCH 1/8] KVM: arm64: nvhe: Save the SPE context early Marc Zyngier
2021-03-05 18:52       ` Marc Zyngier [this message]
2021-03-05 18:52       ` [PATCH 3/8] KVM: arm64: Fix nVHE hyp panic host context restore Marc Zyngier
2021-03-05 18:52       ` [PATCH 4/8] KVM: arm64: Turn kvm_arm_support_pmu_v3() into a static key Marc Zyngier
2021-03-05 18:52       ` [PATCH 5/8] KVM: arm64: Don't access PMSELR_EL0/PMUSERENR_EL0 when no PMU is available Marc Zyngier
2021-03-05 18:52       ` [PATCH 6/8] KVM: arm64: Rename __vgic_v3_get_ich_vtr_el2() to __vgic_v3_get_gic_config() Marc Zyngier
2021-03-05 18:52       ` [PATCH 7/8] KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3 compatibility Marc Zyngier
2021-03-15 12:55         ` Shameerali Kolothum Thodi
2021-03-15 14:36           ` Marc Zyngier
2021-03-05 18:52       ` [PATCH 8/8] KVM: arm64: Fix range alignment when walking page tables Marc Zyngier
2021-03-06  9:50       ` [PATCH 0/8] KVM/arm64 fixes for 5.12, take #1 Paolo Bonzini

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