diff mbox series

[v2,04/43] arm64: RME: Handle Granule Protection Faults (GPFs)

Message ID 20240412084309.1733783-5-steven.price@arm.com (mailing list archive)
State New, archived
Headers show
Series arm64: Support for Arm CCA in KVM | expand

Commit Message

Steven Price April 12, 2024, 8:42 a.m. UTC
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>
---
 arch/arm64/mm/fault.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

Comments

Suzuki K Poulose April 16, 2024, 11:17 a.m. UTC | #1
On 12/04/2024 09:42, Steven Price wrote:
> 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>
> ---
>   arch/arm64/mm/fault.c | 29 ++++++++++++++++++++++++-----
>   1 file changed, 24 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index 8251e2fea9c7..91da0f446dd9 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -765,6 +765,25 @@ 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"	},
> @@ -802,11 +821,11 @@ static const struct fault_info fault_info[] = {
>   	{ do_alignment_fault,	SIGBUS,  BUS_ADRALN,	"alignment fault"		},
>   	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 34"			},
>   	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 35"			},

Should this also be converted to do_gpf_ptw, "GPF at level -1", given we 
support LPA2 ?


> -	{ 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 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"	},


Rest looks fine to me.

Suzuki
Steven Price April 18, 2024, 1:17 p.m. UTC | #2
On 16/04/2024 12:17, Suzuki K Poulose wrote:
> On 12/04/2024 09:42, Steven Price wrote:
>> 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>
>> ---
>>   arch/arm64/mm/fault.c | 29 ++++++++++++++++++++++++-----
>>   1 file changed, 24 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
>> index 8251e2fea9c7..91da0f446dd9 100644
>> --- a/arch/arm64/mm/fault.c
>> +++ b/arch/arm64/mm/fault.c
>> @@ -765,6 +765,25 @@ 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"    },
>> @@ -802,11 +821,11 @@ static const struct fault_info fault_info[] = {
>>       { do_alignment_fault,    SIGBUS,  BUS_ADRALN,    "alignment
>> fault"        },
>>       { do_bad,        SIGKILL, SI_KERNEL,    "unknown 34"            },
>>       { do_bad,        SIGKILL, SI_KERNEL,    "unknown 35"            },
> 
> Should this also be converted to do_gpf_ptw, "GPF at level -1", given we
> support LPA2 ?

Ah, yes I somehow missed that. Although something has gone majorly wrong
if this triggers! ;)

Steve

>> -    { 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 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"    },
> 
> 
> Rest looks fine to me.
> 
> Suzuki
diff mbox series

Patch

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 8251e2fea9c7..91da0f446dd9 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -765,6 +765,25 @@  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"	},
@@ -802,11 +821,11 @@  static const struct fault_info fault_info[] = {
 	{ 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 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"	},