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From: Marc Zyngier <maz@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Santosh Shukla <sashukla@nvidia.com>,
	Gavin Shan <gshan@redhat.com>,
	kvm@vger.kernel.org, Quentin Perret <qperret@google.com>,
	kernel-team@android.com,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	kvmarm@lists.cs.columbia.edu,
	Vladimir Murzin <vladimir.murzin@arm.com>,
	James Morse <james.morse@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	David Brazdil <dbrazdil@google.com>,
	Will Deacon <will@kernel.org>, Qais Yousef <qais.yousef@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>
Subject: [PATCH 06/12] KVM: arm64: Fix masks in stage2_pte_cacheable()
Date: Fri, 30 Oct 2020 16:40:11 +0000	[thread overview]
Message-ID: <20201030164017.244287-7-maz@kernel.org> (raw)
In-Reply-To: <20201030164017.244287-1-maz@kernel.org>

From: Will Deacon <will@kernel.org>

stage2_pte_cacheable() tries to figure out whether the mapping installed
in its 'pte' parameter is cacheable or not. Unfortunately, it fails
miserably because it extracts the memory attributes from the entry using
FIELD_GET(), which returns the attributes shifted down to bit 0, but then
compares this with the unshifted value generated by the PAGE_S2_MEMATTR()
macro.

A direct consequence of this bug is that cache maintenance is silently
skipped, which in turn causes 32-bit guests to crash early on when their
set/way maintenance is trapped but not emulated correctly.

Fix the broken masks by avoiding the use of FIELD_GET() altogether.

Fixes: 6d9d2115c480 ("KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table")
Reported-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20201029144716.30476-1-will@kernel.org
---
 arch/arm64/kvm/hyp/pgtable.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 95141b0d6088..0271b4a3b9fe 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -635,7 +635,7 @@ static void stage2_flush_dcache(void *addr, u64 size)
 
 static bool stage2_pte_cacheable(kvm_pte_t pte)
 {
-	u64 memattr = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR, pte);
+	u64 memattr = pte & KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR;
 	return memattr == PAGE_S2_MEMATTR(NORMAL);
 }
 
-- 
2.28.0


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  parent reply	other threads:[~2020-10-30 16:42 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30 16:40 [GIT PULL] KVM/arm64 fixes for 5.10, take #1 Marc Zyngier
2020-10-30 16:40 ` [PATCH 01/12] KVM: arm64: Don't corrupt tpidr_el2 on failed HVC call Marc Zyngier
2020-10-30 16:40 ` [PATCH 02/12] KVM: arm64: Remove leftover kern_hyp_va() in nVHE TLB invalidation Marc Zyngier
2020-10-30 16:40 ` [PATCH 03/12] KVM: arm64: Drop useless PAN setting on host EL1 to EL2 transition Marc Zyngier
2020-10-30 16:40 ` [PATCH 04/12] KVM: arm64: Allocate stage-2 pgd pages with GFP_KERNEL_ACCOUNT Marc Zyngier
2020-10-30 16:40 ` [PATCH 05/12] KVM: arm64: Fix AArch32 handling of DBGD{CCINT, SCRext} and DBGVCR Marc Zyngier
2020-10-30 16:40 ` Marc Zyngier [this message]
2020-10-30 16:40 ` [PATCH 07/12] KVM: arm64: Use fallback mapping sizes for contiguous huge page sizes Marc Zyngier
2020-10-30 16:40 ` [PATCH 08/12] KVM: arm64: Force PTE mapping on fault resulting in a device mapping Marc Zyngier
2020-10-30 16:40 ` [PATCH 09/12] KVM: arm64: Factor out is_{vhe,nvhe}_hyp_code() Marc Zyngier
2020-10-30 16:40 ` [PATCH 10/12] arm64: cpufeature: reorder cpus_have_{const, final}_cap() Marc Zyngier
2020-10-30 16:40 ` [PATCH 11/12] arm64: cpufeature: upgrade hyp caps to final Marc Zyngier
2020-10-30 16:40 ` [PATCH 12/12] KVM: arm64: Handle Asymmetric AArch32 systems Marc Zyngier
2020-10-31 14:35 ` [GIT PULL] KVM/arm64 fixes for 5.10, take #1 Paolo Bonzini

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