Re: [PATCH v5 04/43] arm64: RME: Handle Granule Protection Faults (GPFs)
From: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Date: 2024-10-24 14:17:51
Also in:
kvm, kvmarm, linux-coco, lkml
Steven Price [off-list ref] 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. [ 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
quoted hunk ↗ jump to hunk
Signed-off-by: Steven Price <steven.price@arm.com> --- 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