From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.235 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792580838; b=Bq91rT/kPpCTwpnQ+y1/ludgXHv/26/QJn6txhc/IZ09kYTD6vudLmkd4nlibwaB/2RZ GrwSGui2H8HAnzCrRmEpDBnaa+XAZTJZK3r7JUMPa0yyPq6SmuJD4JvsBcfxNS4KjeefR DsREE/r+MP7YzanOadRtIONUW3N24nHT6P3mrBNtP0sfTpawzlQfFgBleIFGngrtZ/FOD 5ey/BuBbLJdNuzdWEwN4c+Xm6ZnZIoyITUNVLWPX5nbusJZzQlUhfx++vaU+UW8v9U3HP 0UFlHzliTB7XIPIl7yxCV9CxR14+WJ9pPrRWIETQp6qiR9g+HwTDmNkXF9iJocIBA1g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792580838; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=lfJEvxeugzbMy0UfOmSFFKEhA+PewXL6rgmJ57d1BGY=; b=5DWkKg7lyGM/OUitjW9pIG9Soe3+IbtXNbFEWZ0c8Qn9oMQ0+kOOIep21sNw6dVFDSGJ TxVFFkN7t8stzK127j/0qN76E+DuDkGw1qv5iQ4k45PpXwjZJO6P1dqw/uisSYvA6uDeE 94MJfnVNfB5VX+H4f6MqNG7HyNh8eQfsrLVcdLqFS6Zo2HQBSs7Y8taueZ1DjQI/7O2ok uxJ12LBZ1cI2LRsbqQrIrpikoEtam90aWwUI66XSidOwymhYL/gulG9U71gqXtn0E08Hg 4eKU5w4Ik994ynuKHh/NPXX1FcJKagU+aftwlDTn73SS4j6F4kaDWTDZu4fsLodjMRA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=IaPriw5B; arc=none smtp.remote-ip=95.215.58.235 Received: from mta1.migadu.com (out-235.mta1.migadu.com [95.215.58.235]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A61D2606A31F for ; Wed, 21 Oct 2026 11:07:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A61D2606A31F Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=IaPriw5B X-Envelope-To: kvmarm@lists.linux.dev DKIM-Signature: a=rsa-sha256; bh=Pju20CFh13puHUYFtOtzpLfsAN18NYvnMP/ZNBnwsKA=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792580835; v=1; x=1793185635; b=IaPriw5BfVW9gEFnfu3PD1FlyMHM7/f5hFkSqPNok+4ccVfzjeGnnljf3cWCQ42NgoyUsyAt gp/yB1hle05hRGXFYpea6yXauJn80ffXE8lc7gC8wmumH/FnLLfjqAerP/OeDCHm7n/ZN7+ZNQV rcOnP8dbHEujL7l3+4lYlZ/U= X-Envelope-To: kvmarm@lists.linux.dev Received: by smtp.migadu.com with ESMTPS id 2cc7fc73b5d6669d; Wed, 21 Oct 2026 11:07:15 +0000 X-Mizu-Trace-ID: 2cc7fc73b5d6669d X-Migadu-Flow: FLOW_OUT From: Fuad Tabba To: Marc Zyngier , Oliver Upton , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: Joey Gouly , Suzuki K Poulose , Zenghui Yu , Steffen Eiden , Catalin Marinas , Will Deacon , Mark Rutland , Steven Price , Yang Shi , David Hildenbrand , Lorenzo Stoakes , Fuad Tabba , linux-kernel@vger.kernel.org Subject: [PATCH v2 3/4] KVM: arm64: Sanitise MTE tags when a permission fault installs a mapping Date: Wed, 21 Oct 2026 12:06:59 +0100 Message-ID: <20261021110700.493315-4-fuad.tabba@linux.dev> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261021110700.493315-1-fuad.tabba@linux.dev> References: <20261021110700.493315-1-fuad.tabba@linux.dev> X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The stage-2 fault path sanitises MTE tags only on translation faults, as a permission fault normally just relaxes an existing leaf. However, when the page is backed by a THP, a permission fault at page granule installs a block whose other pages may never have been mapped or sanitised. Once dirty logging is off, a guest write to a page mapped read-only during logging installs the block, and the guest can read the tags those pages' previous owners left. Sanitise whenever the fault path calls kvm_pgtable_stage2_map() rather than relaxing permissions. If the VMM replaces the VMA after the guest takes a permission fault but before vma_lookup(), that path would map and sanitise memory from the new VMA without checking it. Run the VM_MTE_ALLOWED check in kvm_s2_fault_compute_prot() on permission faults too. Fixes: ea7fc1bb1cd1b ("KVM: arm64: Introduce MTE VM feature") Reviewed-by: Lorenzo Stoakes (ARM) Cc: stable@vger.kernel.org Signed-off-by: Fuad Tabba --- arch/arm64/kvm/mmu.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index a551b6bb13c21..6e10aa9913d71 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -2004,7 +2004,7 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd, if (s2fd->nested) *prot = adjust_nested_exec_perms(kvm, s2fd->nested, *prot); - if (!kvm_s2_fault_is_perm(s2fd) && !s2vi->map_non_cacheable && kvm_has_mte(kvm)) { + if (!s2vi->map_non_cacheable && kvm_has_mte(kvm)) { /* Check the VMM hasn't introduced a new disallowed VMA */ if (!s2vi->mte_allowed) return -EFAULT; @@ -2059,9 +2059,6 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, } } - if (!perm_fault_granule && !s2vi->map_non_cacheable && kvm_has_mte(kvm)) - sanitise_mte_tags(kvm, pfn, mapping_size); - /* * Under the premise of getting a FSC_PERM fault, we just need to relax * permissions only if mapping_size equals perm_fault_granule. Otherwise, @@ -2076,6 +2073,9 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, ret = KVM_PGT_FN(kvm_pgtable_stage2_relax_perms)(pgt, gfn_to_gpa(gfn), prot, flags); } else { + if (!s2vi->map_non_cacheable && kvm_has_mte(kvm)) + sanitise_mte_tags(kvm, pfn, mapping_size); + ret = KVM_PGT_FN(kvm_pgtable_stage2_map)(pgt, gfn_to_gpa(gfn), mapping_size, __pfn_to_phys(pfn), prot, memcache, flags); -- 2.47.3