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 2338C21218B; Fri, 25 Oct 2024 13:24:46 +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=1729862689; cv=none; b=Ya+RMqFjEs7ALmQmFDNuZp9qph2VbBxYIanX6NT/ZoHi3fgl1Jy8ZfSiKT8aTAmRS4/zen85wZ3oySXgJpsoMcV2OlfbjZrnpCFqEMqrtSkHKG6iie2SzdCP+3BJnFZgQXs68vrOgOUwCgb82KSXjRGUD4pK+6guiIdWNR5Mys8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729862689; c=relaxed/simple; bh=wD6jUuBlvN6RbhnBKl+0OEQCxIdsQrDQgvnBlzR2yBc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=hwswoXDCJDhatndCLaG2WeHrIFJnLKiOSCwZKFRKtEjSvymcNufeK7fyM+yJoRCwocOgP2MACmoQRmf5I2Mp+JVYdMQ6cyFFLtKuuDx3N/+H7R4ZEx4WnWPG2gsnFE0jWEL3KFlKkg7GQuxYfxI/Qdmgng8HeGhaQFa2BvnHBvw= 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; 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 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 E512C339; Fri, 25 Oct 2024 06:25:15 -0700 (PDT) Received: from [10.1.36.18] (e122027.cambridge.arm.com [10.1.36.18]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C42393F71E; Fri, 25 Oct 2024 06:24:41 -0700 (PDT) Message-ID: Date: Fri, 25 Oct 2024 14:24:39 +0100 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 04/43] arm64: RME: Handle Granule Protection Faults (GPFs) To: "Aneesh Kumar K.V" , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Gavin Shan , Shanker Donthineni , Alper Gun References: <20241004152804.72508-1-steven.price@arm.com> <20241004152804.72508-5-steven.price@arm.com> From: Steven Price Content-Language: en-GB In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 24/10/2024 15:17, Aneesh Kumar K.V wrote: > Steven Price writes: > >> 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. >> > > A non-page walk fault can also be caused by host kernel trying to access a > page which it had delegated before. It would be nice to dump details > like FAR in that case. Right now it shows only the below. While I agree FAR would be handy, this isn't specific to a GPF. arm64_notify_die() takes the FAR, but in the case of a kernel fault ignores it and calls die(). I'm not sure if there's a good reason for it not calling die_kernel_fault() instead which would print the FAR. Or indeed whether the FAR should be passed instead of the ESR (although changing that now would probably be confusing). This affects e.g. do_sea(), do_mem_abort() and others too. It might be worth sending a patch to improve that behaviour, but I think the handling for GPFs of using arm64_notify_die() is correct. Thanks, Steve > [ 285.122310] Internal error: Granule Protection Fault not on table walk: 0000000096000068 [#1] PREEMPT SMP > [ 285.122427] Modules linked in: > [ 285.122512] CPU: 1 UID: 0 PID: 217 Comm: kvm-vcpu-0 Not tainted 6.12.0-rc1-00082-g8461d8333829 #42 > [ 285.122656] Hardware name: FVP Base RevC (DT) > [ 285.122733] pstate: 81400009 (Nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) > [ 285.122871] pc : clear_page+0x18/0x50 > [ 285.122975] lr : kvm_gmem_get_pfn+0xbc/0x190 > [ 285.123110] sp : ffff800082cef900 > [ 285.123182] x29: ffff800082cef910 x28: 0000000090000000 x27: 0000000090000006 > ..... > > -aneesh > >> >> Signed-off-by: Steven Price >> --- >> Changes since v2: >> * Include missing "Granule Protection Fault at level -1" >> --- >> arch/arm64/mm/fault.c | 31 +++++++++++++++++++++++++------ >> 1 file changed, 25 insertions(+), 6 deletions(-) >> >> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c >> index 8b281cf308b3..f9d72a936d48 100644 >> --- a/arch/arm64/mm/fault.c >> +++ b/arch/arm64/mm/fault.c >> @@ -804,6 +804,25 @@ 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); >> + >> + die_kernel_fault(inf->name, far, esr, regs); >> + return 0; >> +} >> + >> +static int do_gpf(unsigned long far, unsigned long esr, struct pt_regs *regs) >> +{ >> + const struct fault_info *inf = esr_to_fault_info(esr); >> + >> + if (!is_el1_instruction_abort(esr) && fixup_exception(regs)) >> + return 0; >> + >> + arm64_notify_die(inf->name, regs, inf->sig, inf->code, far, esr); >> + return 0; >> +} >> + >> 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" }, >> @@ -840,12 +859,12 @@ 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, "Granule Protection Fault at level -1" }, >> + { do_gpf_ptw, SIGKILL, SI_KERNEL, "Granule Protection Fault at level 0" }, >> + { do_gpf_ptw, SIGKILL, SI_KERNEL, "Granule Protection Fault at level 1" }, >> + { do_gpf_ptw, SIGKILL, SI_KERNEL, "Granule Protection Fault at level 2" }, >> + { do_gpf_ptw, SIGKILL, SI_KERNEL, "Granule Protection Fault at level 3" }, >> + { do_gpf, SIGBUS, SI_KERNEL, "Granule Protection Fault not on table walk" }, >> { 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" }, >> -- >> 2.34.1