| Message ID | 20241004152804.72508-5-steven.price@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Support for Arm CCA in KVM | expand |
Steven Price <steven.price@arm.com> 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 > > 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
On 24/10/2024 15:17, Aneesh Kumar K.V wrote: > Steven Price <steven.price@arm.com> 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 <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
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" },
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. 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(-)