From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 915AA344052; Sun, 13 Sep 2026 07:05:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789283124; cv=none; b=R/xgUd7tcZp+yeMhckup6xw8ZahOot69unZopWgK6Yyu3Dq8JpYVzqQLccnUaZ4o+P9jxn3m/+vCdKN70KpGqOVcMED6jMv+SfGYHL0iqI/MEKqQ7WTTSwIsHRJDeHAN8u+dpOlWShOZNe5Xwulc2+V+3meMBWwvepl4uNn5xNE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789283124; c=relaxed/simple; bh=tXmzQ9/0zxImuwG5nlQfSSjAFgmIBS5AnTHtSJv6yLk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=psYcWo9cE9vQRMVM230IBFzIWNpa5+LRVkbPaDNwN5SrRwn4jvQGVpyDY5WUmaNPpqQY7OfI6jrzg8xCs4aIl5HyQf3CHfZnU2XOtXXJAAKA1cmzB3qZnsdXste0SRUlW6vkJrfyBmzaiqTe6ijoV9dP+pn/qWHeKs/iXNNLqQk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=fKYeFqPh; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="fKYeFqPh" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D88F5153B; Sun, 13 Sep 2026 00:05:16 -0700 (PDT) Received: from ewhatever.cambridge.arm.com (ewhatever.cambridge.arm.com [10.2.197.99]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 096833F7D8; Sun, 13 Sep 2026 00:05:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1789283120; bh=tXmzQ9/0zxImuwG5nlQfSSjAFgmIBS5AnTHtSJv6yLk=; h=From:To:Cc:Subject:Date:From; b=fKYeFqPh3Nbti/qjh+YehqPr6Aca/4iAqF2MXvYA0u+kaAREt8vNj+T8KAi3a6Rly rBcuzC95jeKQhJCf5FDEUVOmoK/RbImi7u0g+hnQr9U8v3H4AdsrkPf2FIlVF851S2 DZzNOKDUFBta4oUb0hFRQDPRg0PpDM0aJ8FiPpsE= From: Suzuki K Poulose To: kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: maz@kernel.org, will@kernel.org, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, steven.price@arm.com, aneesh.kumar@kernel.org, oupton@kernel.org, gshan@redhat.com, joey.gouly@arm.com, tabba@google.com, yuzenghui@huawei.com, linux-coco@lists.linux.dev, gankulkarni@os.amperecomputing.com, sdonthineni@nvidia.com, alpergun@google.com, fj0570is@fujitsu.com, WeiLin.Chang@arm.com, lpieralisi@kernel.org, enju.kohei@fujitsu.com, Suzuki K Poulose Subject: [PATCH v18] arm64: mm: Handle Granule Protection Faults (GPFs) Date: Sun, 13 Sep 2026 08:04:58 +0100 Message-ID: <20260913070459.2547407-1-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Steven Price If the host attempts to access granules that have been delegated for use in a realm these accesses will be caught and will trigger a Granule Protection Fault (GPF). A fault during a page walk signals a bug in the kernel and is handled by oopsing the kernel. A non-page walk fault could be caused by user space having access to a page which has been delegated to the kernel and will trigger a SIGBUS to allow debugging why user space is trying to access a delegated page. There is work in progress to unmap the guest_memfd backed private pages from the linear map. Until we get that support, we could get spurious GPFs from within the kernel, e.g., load_unaligned_zeropad(). So, try to fix them up for now. Reviewed-by: Suzuki K Poulose Reviewed-by: Gavin Shan Reviewed-by: Catalin Marinas Signed-off-by: Steven Price Signed-off-by: Suzuki K Poulose --- Changes since v17: * Pass untagged address to die_kernel_fault() - Sashiko * Explicitly check !user_mode() for fixups - Catalin * Switch to BUS_OBJERR for si_code from SI_KERNEL - Catalin * Clarify the commit description about the upcoming work on unmapping guest_memfd backed pages from linear map Changes since v16: * Update the commit description to indicate why we try to fixup GPFs Changes since v10: * Don't call arm64_notify_die() in do_gpf() but simply return 1. Changes since v2: * Include missing "Granule Protection Fault at level -1" --- arch/arm64/mm/fault.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 75c3e463df2ef..dc3a87902a60c 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -914,6 +914,24 @@ static int do_tag_check_fault(unsigned long far, unsigned long esr, return 0; } +static int do_gpf_ptw(unsigned long far, unsigned long esr, struct pt_regs *regs) +{ + const struct fault_info *inf = esr_to_fault_info(esr); + unsigned long addr = untagged_addr(far); + + die_kernel_fault(inf->name, addr, esr, regs); + return 0; +} + +static int do_gpf(unsigned long far, unsigned long esr, struct pt_regs *regs) +{ + if (!user_mode(regs) && !is_el1_instruction_abort(esr) && + fixup_exception(regs, esr)) + return 0; + + return 1; +} + static const struct fault_info fault_info[] = { { do_bad, SIGKILL, SI_KERNEL, "ttbr address size fault" }, { do_bad, SIGKILL, SI_KERNEL, "level 1 address size fault" }, @@ -950,12 +968,12 @@ static const struct fault_info fault_info[] = { { do_bad, SIGKILL, SI_KERNEL, "unknown 32" }, { do_alignment_fault, SIGBUS, BUS_ADRALN, "alignment fault" }, { do_bad, SIGKILL, SI_KERNEL, "unknown 34" }, - { do_bad, SIGKILL, SI_KERNEL, "unknown 35" }, - { do_bad, SIGKILL, SI_KERNEL, "unknown 36" }, - { do_bad, SIGKILL, SI_KERNEL, "unknown 37" }, - { do_bad, SIGKILL, SI_KERNEL, "unknown 38" }, - { do_bad, SIGKILL, SI_KERNEL, "unknown 39" }, - { do_bad, SIGKILL, SI_KERNEL, "unknown 40" }, + { do_gpf_ptw, SIGKILL, SI_KERNEL, "level -1 granule protection fault (translation table walk)" }, + { do_gpf_ptw, SIGKILL, SI_KERNEL, "level 0 granule protection fault (translation table walk)" }, + { do_gpf_ptw, SIGKILL, SI_KERNEL, "level 1 granule protection fault (translation table walk)" }, + { do_gpf_ptw, SIGKILL, SI_KERNEL, "level 2 granule protection fault (translation table walk)" }, + { do_gpf_ptw, SIGKILL, SI_KERNEL, "level 3 granule protection fault (translation table walk)" }, + { do_gpf, SIGBUS, BUS_OBJERR, "granule protection fault" }, { do_bad, SIGKILL, SI_KERNEL, "level -1 address size fault" }, { do_bad, SIGKILL, SI_KERNEL, "unknown 42" }, { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level -1 translation fault" }, -- 2.43.0