[v6,4/6] arm64/kvm: add a userspace option to enable pointer authentication
diff mbox series

Message ID 1550568271-5319-5-git-send-email-amit.kachhap@arm.com
State New
Headers show
Series
  • Add ARMv8.3 pointer authentication for kvm guest
Related show

Commit Message

Amit Daniel Kachhap Feb. 19, 2019, 9:24 a.m. UTC
This feature will allow the KVM guest to allow the handling of
pointer authentication instructions or to treat them as undefined
if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to
supply this parameter instead of creating a new API.

A new register is not created to pass this parameter via
SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH)
supplied is enough to enable this feature.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Christoffer Dall <christoffer.dall@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
---
 Documentation/arm64/pointer-authentication.txt |  9 +++++----
 Documentation/virtual/kvm/api.txt              |  4 ++++
 arch/arm64/include/asm/kvm_host.h              |  3 ++-
 arch/arm64/include/uapi/asm/kvm.h              |  1 +
 arch/arm64/kvm/handle_exit.c                   |  2 +-
 arch/arm64/kvm/hyp/ptrauth-sr.c                | 16 +++++++++++++++-
 arch/arm64/kvm/reset.c                         |  3 +++
 arch/arm64/kvm/sys_regs.c                      | 26 +++++++++++++-------------
 include/uapi/linux/kvm.h                       |  1 +
 9 files changed, 45 insertions(+), 20 deletions(-)

Comments

Mark Rutland Feb. 21, 2019, 12:34 p.m. UTC | #1
On Tue, Feb 19, 2019 at 02:54:29PM +0530, Amit Daniel Kachhap wrote:
> This feature will allow the KVM guest to allow the handling of
> pointer authentication instructions or to treat them as undefined
> if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to
> supply this parameter instead of creating a new API.
> 
> A new register is not created to pass this parameter via
> SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH)
> supplied is enough to enable this feature.
> 
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Christoffer Dall <christoffer.dall@arm.com>
> Cc: kvmarm@lists.cs.columbia.edu
> ---
>  Documentation/arm64/pointer-authentication.txt |  9 +++++----
>  Documentation/virtual/kvm/api.txt              |  4 ++++
>  arch/arm64/include/asm/kvm_host.h              |  3 ++-
>  arch/arm64/include/uapi/asm/kvm.h              |  1 +
>  arch/arm64/kvm/handle_exit.c                   |  2 +-
>  arch/arm64/kvm/hyp/ptrauth-sr.c                | 16 +++++++++++++++-
>  arch/arm64/kvm/reset.c                         |  3 +++
>  arch/arm64/kvm/sys_regs.c                      | 26 +++++++++++++-------------
>  include/uapi/linux/kvm.h                       |  1 +
>  9 files changed, 45 insertions(+), 20 deletions(-)
> 
> diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt
> index a25cd21..0529a7d 100644
> --- a/Documentation/arm64/pointer-authentication.txt
> +++ b/Documentation/arm64/pointer-authentication.txt
> @@ -82,7 +82,8 @@ pointers).
>  Virtualization
>  --------------
>  
> -Pointer authentication is not currently supported in KVM guests. KVM
> -will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of
> -the feature will result in an UNDEFINED exception being injected into
> -the guest.
> +Pointer authentication is enabled in KVM guest when virtual machine is
> +created by passing a flag (KVM_ARM_VCPU_PTRAUTH) requesting this feature
> +to be enabled. Without this flag, pointer authentication is not enabled
> +in KVM guests and attempted use of the feature will result in an UNDEFINED
> +exception being injected into the guest.
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 356156f..1e646fb 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -2642,6 +2642,10 @@ Possible features:
>  	  Depends on KVM_CAP_ARM_PSCI_0_2.
>  	- KVM_ARM_VCPU_PMU_V3: Emulate PMUv3 for the CPU.
>  	  Depends on KVM_CAP_ARM_PMU_V3.
> +	- KVM_ARM_VCPU_PTRAUTH: Emulate Pointer authentication for the CPU.
> +	  Depends on KVM_CAP_ARM_PTRAUTH and only on arm64 architecture. If
> +	  set, then the KVM guest allows the execution of pointer authentication
> +	  instructions. Otherwise, KVM treats these instructions as undefined.

I think that we should have separate flags for address auth and generic
auth, to match the ID register split.

For now, we can have KVM only support the case where both are set, but
it gives us freedom to support either in isolation if we have to in
future, without an ABI break.

Thanks,
Mark.
Dave Martin Feb. 21, 2019, 3:53 p.m. UTC | #2
On Tue, Feb 19, 2019 at 02:54:29PM +0530, Amit Daniel Kachhap wrote:
> This feature will allow the KVM guest to allow the handling of
> pointer authentication instructions or to treat them as undefined
> if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to
> supply this parameter instead of creating a new API.
> 
> A new register is not created to pass this parameter via
> SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH)
> supplied is enough to enable this feature.
> 
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Christoffer Dall <christoffer.dall@arm.com>
> Cc: kvmarm@lists.cs.columbia.edu
> ---
>  Documentation/arm64/pointer-authentication.txt |  9 +++++----
>  Documentation/virtual/kvm/api.txt              |  4 ++++
>  arch/arm64/include/asm/kvm_host.h              |  3 ++-
>  arch/arm64/include/uapi/asm/kvm.h              |  1 +
>  arch/arm64/kvm/handle_exit.c                   |  2 +-
>  arch/arm64/kvm/hyp/ptrauth-sr.c                | 16 +++++++++++++++-
>  arch/arm64/kvm/reset.c                         |  3 +++
>  arch/arm64/kvm/sys_regs.c                      | 26 +++++++++++++-------------
>  include/uapi/linux/kvm.h                       |  1 +
>  9 files changed, 45 insertions(+), 20 deletions(-)
> 

[...]

> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 1bacf78..2768a53 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -43,7 +43,7 @@
>  
>  #define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
>  
> -#define KVM_VCPU_MAX_FEATURES 4
> +#define KVM_VCPU_MAX_FEATURES 5
>  
>  #define KVM_REQ_SLEEP \
>  	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
> @@ -451,6 +451,7 @@ static inline bool kvm_arch_requires_vhe(void)
>  	return false;
>  }
>  
> +bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu);
>  static inline bool kvm_supports_ptrauth(void)
>  {
>  	return has_vhe() && system_supports_address_auth() &&

[...]

> diff --git a/arch/arm64/kvm/hyp/ptrauth-sr.c b/arch/arm64/kvm/hyp/ptrauth-sr.c
> index 528ee6e..6846a23 100644
> --- a/arch/arm64/kvm/hyp/ptrauth-sr.c
> +++ b/arch/arm64/kvm/hyp/ptrauth-sr.c
> @@ -93,9 +93,23 @@ void kvm_arm_vcpu_ptrauth_reset(struct kvm_vcpu *vcpu)

[...]

> +/**
> + * kvm_arm_vcpu_ptrauth_allowed - checks if ptrauth feature is allowed by user
> + *
> + * @vcpu: The VCPU pointer
> + *
> + * This function will be used to check userspace option to have ptrauth or not
> + * in the guest kernel.
> + */
> +bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu)
> +{
> +	return kvm_supports_ptrauth() &&
> +		test_bit(KVM_ARM_VCPU_PTRAUTH, vcpu->arch.features);
> +}

Nit: for SVE is called the equivalent helper vcpu_has_sve(vcpu).

Neither naming is more correct, but it would make sense to be
consistent.  We will likely accumulate more of these vcpu feature
predicates over time.

Given that this is trivial and will be used all over the place, it
probably makes sense to define it in kvm_host.h rather than having it
out of line in a separate C file.

> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index b72a3dd..987e0c3c 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -91,6 +91,9 @@ int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_ARM_VM_IPA_SIZE:
>  		r = kvm_ipa_limit;
>  		break;
> +	case KVM_CAP_ARM_PTRAUTH:
> +		r = kvm_supports_ptrauth();
> +		break;
>  	default:
>  		r = 0;
>  	}
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 12529df..f7bcc60 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1055,7 +1055,7 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
>  }
>  
>  /* Read a sanitised cpufeature ID register by sys_reg_desc */
> -static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
> +static u64 read_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_desc const *r, bool raz)
>  {
>  	u32 id = sys_reg((u32)r->Op0, (u32)r->Op1,
>  			 (u32)r->CRn, (u32)r->CRm, (u32)r->Op2);
> @@ -1071,7 +1071,7 @@ static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
>  					 (0xfUL << ID_AA64ISAR1_API_SHIFT) |
>  					 (0xfUL << ID_AA64ISAR1_GPA_SHIFT) |
>  					 (0xfUL << ID_AA64ISAR1_GPI_SHIFT);
> -		if (!kvm_supports_ptrauth()) {
> +		if (!kvm_arm_vcpu_ptrauth_allowed(vcpu)) {
>  			kvm_debug("ptrauth unsupported for guests, suppressing\n");
>  			val &= ~ptrauth_mask;
>  		}
> @@ -1095,7 +1095,7 @@ static bool __access_id_reg(struct kvm_vcpu *vcpu,
>  	if (p->is_write)
>  		return write_to_read_only(vcpu, p, r);
>  
> -	p->regval = read_id_reg(r, raz);
> +	p->regval = read_id_reg(vcpu, r, raz);
>  	return true;
>  }

The SVE KVM series makes various overlapping changes to propagate vcpuo
into the relevant places, but hopefully the rebase is not too painful.
Many of the changes are probably virtually identical between the two
series.

See for example [1].  Maybe you could cherry-pick and drop the
equivalent changes here (though if your series is picked up first, I
will live with it ;)

[...]

Cheers
---Dave


[1] [PATCH v5 10/26] KVM: arm64: Propagate vcpu into read_id_reg()
https://lists.cs.columbia.edu/pipermail/kvmarm/2019-February/034687.html
James Morse Feb. 26, 2019, 6:33 p.m. UTC | #3
Hi Amit,

On 19/02/2019 09:24, Amit Daniel Kachhap wrote:
> This feature will allow the KVM guest to allow the handling of
> pointer authentication instructions or to treat them as undefined
> if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to
> supply this parameter instead of creating a new API.
> 
> A new register is not created to pass this parameter via
> SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH)
> supplied is enough to enable this feature.

and an attempt to restore the id register with the other version would fail.


> diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt
> index a25cd21..0529a7d 100644
> --- a/Documentation/arm64/pointer-authentication.txt
> +++ b/Documentation/arm64/pointer-authentication.txt
> @@ -82,7 +82,8 @@ pointers).
>  Virtualization
>  --------------
>  
> -Pointer authentication is not currently supported in KVM guests. KVM
> -will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of
> -the feature will result in an UNDEFINED exception being injected into
> -the guest.

> +Pointer authentication is enabled in KVM guest when virtual machine is
> +created by passing a flag (KVM_ARM_VCPU_PTRAUTH)

(This is still mixing VM and VCPU)


> + requesting this feature to be enabled.

.. on each vcpu?


> +Without this flag, pointer authentication is not enabled
> +in KVM guests and attempted use of the feature will result in an UNDEFINED
> +exception being injected into the guest.

'guests' here suggests its a VM property. If you set it on some VCPU but not others KVM
will generate undefs instead of enabling the feature. (which is the right thing to do)

I think it needs to be clear this is a per-vcpu property.


> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index 97c3478..5f82ca1 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -102,6 +102,7 @@ struct kvm_regs {
>  #define KVM_ARM_VCPU_EL1_32BIT		1 /* CPU running a 32bit VM */
>  #define KVM_ARM_VCPU_PSCI_0_2		2 /* CPU uses PSCI v0.2 */
>  #define KVM_ARM_VCPU_PMU_V3		3 /* Support guest PMUv3 */

> +#define KVM_ARM_VCPU_PTRAUTH		4 /* VCPU uses address authentication */

Just address authentication? I agree with Mark we should have two bits to match what gets
exposed to EL0. One would then be address, the other generic.


> diff --git a/arch/arm64/kvm/hyp/ptrauth-sr.c b/arch/arm64/kvm/hyp/ptrauth-sr.c
> index 528ee6e..6846a23 100644
> --- a/arch/arm64/kvm/hyp/ptrauth-sr.c
> +++ b/arch/arm64/kvm/hyp/ptrauth-sr.c
> @@ -93,9 +93,23 @@ void kvm_arm_vcpu_ptrauth_reset(struct kvm_vcpu *vcpu)

> +/**
> + * kvm_arm_vcpu_ptrauth_allowed - checks if ptrauth feature is allowed by user
> + *
> + * @vcpu: The VCPU pointer
> + *
> + * This function will be used to check userspace option to have ptrauth or not
> + * in the guest kernel.
> + */
> +bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu)
> +{
> +	return kvm_supports_ptrauth() &&
> +		test_bit(KVM_ARM_VCPU_PTRAUTH, vcpu->arch.features);
> +}

This isn't used from world-switch, could it be moved to guest.c?


> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 12529df..f7bcc60 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1055,7 +1055,7 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
>  }
>  
>  /* Read a sanitised cpufeature ID register by sys_reg_desc */
> -static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
> +static u64 read_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_desc const *r, bool raz)

(It might be easier on the reviewer to move these mechanical changes to an earlier patch)


Looks good,

Thanks,

James
Amit Daniel Kachhap Feb. 28, 2019, 9:25 a.m. UTC | #4
Hi,

On 2/21/19 6:04 PM, Mark Rutland wrote:
> On Tue, Feb 19, 2019 at 02:54:29PM +0530, Amit Daniel Kachhap wrote:
>> This feature will allow the KVM guest to allow the handling of
>> pointer authentication instructions or to treat them as undefined
>> if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to
>> supply this parameter instead of creating a new API.
>>
>> A new register is not created to pass this parameter via
>> SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH)
>> supplied is enough to enable this feature.
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Marc Zyngier <marc.zyngier@arm.com>
>> Cc: Christoffer Dall <christoffer.dall@arm.com>
>> Cc: kvmarm@lists.cs.columbia.edu
>> ---
>>   Documentation/arm64/pointer-authentication.txt |  9 +++++----
>>   Documentation/virtual/kvm/api.txt              |  4 ++++
>>   arch/arm64/include/asm/kvm_host.h              |  3 ++-
>>   arch/arm64/include/uapi/asm/kvm.h              |  1 +
>>   arch/arm64/kvm/handle_exit.c                   |  2 +-
>>   arch/arm64/kvm/hyp/ptrauth-sr.c                | 16 +++++++++++++++-
>>   arch/arm64/kvm/reset.c                         |  3 +++
>>   arch/arm64/kvm/sys_regs.c                      | 26 +++++++++++++-------------
>>   include/uapi/linux/kvm.h                       |  1 +
>>   9 files changed, 45 insertions(+), 20 deletions(-)
>>
>> diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt
>> index a25cd21..0529a7d 100644
>> --- a/Documentation/arm64/pointer-authentication.txt
>> +++ b/Documentation/arm64/pointer-authentication.txt
>> @@ -82,7 +82,8 @@ pointers).
>>   Virtualization
>>   --------------
>>   
>> -Pointer authentication is not currently supported in KVM guests. KVM
>> -will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of
>> -the feature will result in an UNDEFINED exception being injected into
>> -the guest.
>> +Pointer authentication is enabled in KVM guest when virtual machine is
>> +created by passing a flag (KVM_ARM_VCPU_PTRAUTH) requesting this feature
>> +to be enabled. Without this flag, pointer authentication is not enabled
>> +in KVM guests and attempted use of the feature will result in an UNDEFINED
>> +exception being injected into the guest.
>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>> index 356156f..1e646fb 100644
>> --- a/Documentation/virtual/kvm/api.txt
>> +++ b/Documentation/virtual/kvm/api.txt
>> @@ -2642,6 +2642,10 @@ Possible features:
>>   	  Depends on KVM_CAP_ARM_PSCI_0_2.
>>   	- KVM_ARM_VCPU_PMU_V3: Emulate PMUv3 for the CPU.
>>   	  Depends on KVM_CAP_ARM_PMU_V3.
>> +	- KVM_ARM_VCPU_PTRAUTH: Emulate Pointer authentication for the CPU.
>> +	  Depends on KVM_CAP_ARM_PTRAUTH and only on arm64 architecture. If
>> +	  set, then the KVM guest allows the execution of pointer authentication
>> +	  instructions. Otherwise, KVM treats these instructions as undefined.
> 
> I think that we should have separate flags for address auth and generic
> auth, to match the ID register split.
> 
> For now, we can have KVM only support the case where both are set, but
> it gives us freedom to support either in isolation if we have to in
> future, without an ABI break.
yes agree with you about having two address and generic ptrauth flags. 
Will add in next iteration.

Thanks,
Amit D
> 
> Thanks,
> Mark.
>
Amit Daniel Kachhap March 1, 2019, 9:41 a.m. UTC | #5
Hi,

On 2/21/19 9:23 PM, Dave Martin wrote:
> On Tue, Feb 19, 2019 at 02:54:29PM +0530, Amit Daniel Kachhap wrote:
>> This feature will allow the KVM guest to allow the handling of
>> pointer authentication instructions or to treat them as undefined
>> if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to
>> supply this parameter instead of creating a new API.
>>
>> A new register is not created to pass this parameter via
>> SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH)
>> supplied is enough to enable this feature.
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Marc Zyngier <marc.zyngier@arm.com>
>> Cc: Christoffer Dall <christoffer.dall@arm.com>
>> Cc: kvmarm@lists.cs.columbia.edu
>> ---
>>   Documentation/arm64/pointer-authentication.txt |  9 +++++----
>>   Documentation/virtual/kvm/api.txt              |  4 ++++
>>   arch/arm64/include/asm/kvm_host.h              |  3 ++-
>>   arch/arm64/include/uapi/asm/kvm.h              |  1 +
>>   arch/arm64/kvm/handle_exit.c                   |  2 +-
>>   arch/arm64/kvm/hyp/ptrauth-sr.c                | 16 +++++++++++++++-
>>   arch/arm64/kvm/reset.c                         |  3 +++
>>   arch/arm64/kvm/sys_regs.c                      | 26 +++++++++++++-------------
>>   include/uapi/linux/kvm.h                       |  1 +
>>   9 files changed, 45 insertions(+), 20 deletions(-)
>>
> 
> [...]
> 
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 1bacf78..2768a53 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -43,7 +43,7 @@
>>   
>>   #define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
>>   
>> -#define KVM_VCPU_MAX_FEATURES 4
>> +#define KVM_VCPU_MAX_FEATURES 5
>>   
>>   #define KVM_REQ_SLEEP \
>>   	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
>> @@ -451,6 +451,7 @@ static inline bool kvm_arch_requires_vhe(void)
>>   	return false;
>>   }
>>   
>> +bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu);
>>   static inline bool kvm_supports_ptrauth(void)
>>   {
>>   	return has_vhe() && system_supports_address_auth() &&
> 
> [...]
> 
>> diff --git a/arch/arm64/kvm/hyp/ptrauth-sr.c b/arch/arm64/kvm/hyp/ptrauth-sr.c
>> index 528ee6e..6846a23 100644
>> --- a/arch/arm64/kvm/hyp/ptrauth-sr.c
>> +++ b/arch/arm64/kvm/hyp/ptrauth-sr.c
>> @@ -93,9 +93,23 @@ void kvm_arm_vcpu_ptrauth_reset(struct kvm_vcpu *vcpu)
> 
> [...]
> 
>> +/**
>> + * kvm_arm_vcpu_ptrauth_allowed - checks if ptrauth feature is allowed by user
>> + *
>> + * @vcpu: The VCPU pointer
>> + *
>> + * This function will be used to check userspace option to have ptrauth or not
>> + * in the guest kernel.
>> + */
>> +bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu)
>> +{
>> +	return kvm_supports_ptrauth() &&
>> +		test_bit(KVM_ARM_VCPU_PTRAUTH, vcpu->arch.features);
>> +}
> 
> Nit: for SVE is called the equivalent helper vcpu_has_sve(vcpu).
> 
> Neither naming is more correct, but it would make sense to be
> consistent.  We will likely accumulate more of these vcpu feature
> predicates over time.
> 
> Given that this is trivial and will be used all over the place, it
> probably makes sense to define it in kvm_host.h rather than having it
> out of line in a separate C file.
Ok I checked the SVE implementation. vcpu_has_ptrauth macro make more sense.
> 
>> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
>> index b72a3dd..987e0c3c 100644
>> --- a/arch/arm64/kvm/reset.c
>> +++ b/arch/arm64/kvm/reset.c
>> @@ -91,6 +91,9 @@ int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>   	case KVM_CAP_ARM_VM_IPA_SIZE:
>>   		r = kvm_ipa_limit;
>>   		break;
>> +	case KVM_CAP_ARM_PTRAUTH:
>> +		r = kvm_supports_ptrauth();
>> +		break;
>>   	default:
>>   		r = 0;
>>   	}
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index 12529df..f7bcc60 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -1055,7 +1055,7 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
>>   }
>>   
>>   /* Read a sanitised cpufeature ID register by sys_reg_desc */
>> -static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
>> +static u64 read_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_desc const *r, bool raz)
>>   {
>>   	u32 id = sys_reg((u32)r->Op0, (u32)r->Op1,
>>   			 (u32)r->CRn, (u32)r->CRm, (u32)r->Op2);
>> @@ -1071,7 +1071,7 @@ static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
>>   					 (0xfUL << ID_AA64ISAR1_API_SHIFT) |
>>   					 (0xfUL << ID_AA64ISAR1_GPA_SHIFT) |
>>   					 (0xfUL << ID_AA64ISAR1_GPI_SHIFT);
>> -		if (!kvm_supports_ptrauth()) {
>> +		if (!kvm_arm_vcpu_ptrauth_allowed(vcpu)) {
>>   			kvm_debug("ptrauth unsupported for guests, suppressing\n");
>>   			val &= ~ptrauth_mask;
>>   		}
>> @@ -1095,7 +1095,7 @@ static bool __access_id_reg(struct kvm_vcpu *vcpu,
>>   	if (p->is_write)
>>   		return write_to_read_only(vcpu, p, r);
>>   
>> -	p->regval = read_id_reg(r, raz);
>> +	p->regval = read_id_reg(vcpu, r, raz);
>>   	return true;
>>   }
> 
> The SVE KVM series makes various overlapping changes to propagate vcpuo
> into the relevant places, but hopefully the rebase is not too painful.
> Many of the changes are probably virtually identical between the two
> series.
> 
> See for example [1].  Maybe you could cherry-pick and drop the
> equivalent changes here (though if your series is picked up first, I
> will live with it ;)
Yes no issue. I will cherry-pick your specific patch and rebase mine on it.

Thanks,
Amit D
> 
> [...]
> 
> Cheers
> ---Dave
> 
> 
> [1] [PATCH v5 10/26] KVM: arm64: Propagate vcpu into read_id_reg()
> https://lists.cs.columbia.edu/pipermail/kvmarm/2019-February/034687.html
>
Dave Martin March 1, 2019, 12:22 p.m. UTC | #6
On Fri, Mar 01, 2019 at 09:41:20AM +0000, Amit Daniel Kachhap wrote:
> Hi,
>
> On 2/21/19 9:23 PM, Dave Martin wrote:
> > On Tue, Feb 19, 2019 at 02:54:29PM +0530, Amit Daniel Kachhap wrote:
> >> This feature will allow the KVM guest to allow the handling of
> >> pointer authentication instructions or to treat them as undefined
> >> if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to
> >> supply this parameter instead of creating a new API.
> >>
> >> A new register is not created to pass this parameter via
> >> SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH)
> >> supplied is enough to enable this feature.
> >>
> >> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
> >> Cc: Mark Rutland <mark.rutland@arm.com>
> >> Cc: Marc Zyngier <marc.zyngier@arm.com>
> >> Cc: Christoffer Dall <christoffer.dall@arm.com>
> >> Cc: kvmarm@lists.cs.columbia.edu

[...]

> >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> >> index 12529df..f7bcc60 100644
> >> --- a/arch/arm64/kvm/sys_regs.c
> >> +++ b/arch/arm64/kvm/sys_regs.c
> >> @@ -1055,7 +1055,7 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
> >>   }
> >>
> >>   /* Read a sanitised cpufeature ID register by sys_reg_desc */
> >> -static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
> >> +static u64 read_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_desc const *r, bool raz)
> >>   {
> >>   u32 id = sys_reg((u32)r->Op0, (u32)r->Op1,
> >>    (u32)r->CRn, (u32)r->CRm, (u32)r->Op2);
> >> @@ -1071,7 +1071,7 @@ static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
> >>    (0xfUL << ID_AA64ISAR1_API_SHIFT) |
> >>    (0xfUL << ID_AA64ISAR1_GPA_SHIFT) |
> >>    (0xfUL << ID_AA64ISAR1_GPI_SHIFT);
> >> -if (!kvm_supports_ptrauth()) {
> >> +if (!kvm_arm_vcpu_ptrauth_allowed(vcpu)) {
> >>   kvm_debug("ptrauth unsupported for guests, suppressing\n");
> >>   val &= ~ptrauth_mask;
> >>   }
> >> @@ -1095,7 +1095,7 @@ static bool __access_id_reg(struct kvm_vcpu *vcpu,
> >>   if (p->is_write)
> >>   return write_to_read_only(vcpu, p, r);
> >>
> >> -p->regval = read_id_reg(r, raz);
> >> +p->regval = read_id_reg(vcpu, r, raz);
> >>   return true;
> >>   }
> >
> > The SVE KVM series makes various overlapping changes to propagate vcpuo
> > into the relevant places, but hopefully the rebase is not too painful.
> > Many of the changes are probably virtually identical between the two
> > series.
> >
> > See for example [1].  Maybe you could cherry-pick and drop the
> > equivalent changes here (though if your series is picked up first, I
> > will live with it ;)
> Yes no issue. I will cherry-pick your specific patch and rebase mine on it.

OK, thanks.

Unfortunately it is likely to churn a bit due to review-- my v6 series
will rename some stuff.  Hopefully it will be stable from then on.

Cheers
---Dave
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Amit Daniel Kachhap March 4, 2019, 10:56 a.m. UTC | #7
Hi James,

On 2/27/19 12:03 AM, James Morse wrote:
> Hi Amit,
> 
> On 19/02/2019 09:24, Amit Daniel Kachhap wrote:
>> This feature will allow the KVM guest to allow the handling of
>> pointer authentication instructions or to treat them as undefined
>> if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to
>> supply this parameter instead of creating a new API.
>>
>> A new register is not created to pass this parameter via
>> SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH)
>> supplied is enough to enable this feature.
> 
> and an attempt to restore the id register with the other version would fail.
> 
> 
>> diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt
>> index a25cd21..0529a7d 100644
>> --- a/Documentation/arm64/pointer-authentication.txt
>> +++ b/Documentation/arm64/pointer-authentication.txt
>> @@ -82,7 +82,8 @@ pointers).
>>   Virtualization
>>   --------------
>>   
>> -Pointer authentication is not currently supported in KVM guests. KVM
>> -will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of
>> -the feature will result in an UNDEFINED exception being injected into
>> -the guest.
> 
>> +Pointer authentication is enabled in KVM guest when virtual machine is
>> +created by passing a flag (KVM_ARM_VCPU_PTRAUTH)
> 
> (This is still mixing VM and VCPU)
> 
> 
>> + requesting this feature to be enabled.
> 
> .. on each vcpu?
> 
> 
>> +Without this flag, pointer authentication is not enabled
>> +in KVM guests and attempted use of the feature will result in an UNDEFINED
>> +exception being injected into the guest.
> 
> 'guests' here suggests its a VM property. If you set it on some VCPU but not others KVM
> will generate undefs instead of enabling the feature. (which is the right thing to do)
> 
> I think it needs to be clear this is a per-vcpu property.
ok.
> 
> 
>> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
>> index 97c3478..5f82ca1 100644
>> --- a/arch/arm64/include/uapi/asm/kvm.h
>> +++ b/arch/arm64/include/uapi/asm/kvm.h
>> @@ -102,6 +102,7 @@ struct kvm_regs {
>>   #define KVM_ARM_VCPU_EL1_32BIT		1 /* CPU running a 32bit VM */
>>   #define KVM_ARM_VCPU_PSCI_0_2		2 /* CPU uses PSCI v0.2 */
>>   #define KVM_ARM_VCPU_PMU_V3		3 /* Support guest PMUv3 */
> 
>> +#define KVM_ARM_VCPU_PTRAUTH		4 /* VCPU uses address authentication */
> 
> Just address authentication? I agree with Mark we should have two bits to match what gets
> exposed to EL0. One would then be address, the other generic.
ok.
> 
> 
>> diff --git a/arch/arm64/kvm/hyp/ptrauth-sr.c b/arch/arm64/kvm/hyp/ptrauth-sr.c
>> index 528ee6e..6846a23 100644
>> --- a/arch/arm64/kvm/hyp/ptrauth-sr.c
>> +++ b/arch/arm64/kvm/hyp/ptrauth-sr.c
>> @@ -93,9 +93,23 @@ void kvm_arm_vcpu_ptrauth_reset(struct kvm_vcpu *vcpu)
> 
>> +/**
>> + * kvm_arm_vcpu_ptrauth_allowed - checks if ptrauth feature is allowed by user
>> + *
>> + * @vcpu: The VCPU pointer
>> + *
>> + * This function will be used to check userspace option to have ptrauth or not
>> + * in the guest kernel.
>> + */
>> +bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu)
>> +{
>> +	return kvm_supports_ptrauth() &&
>> +		test_bit(KVM_ARM_VCPU_PTRAUTH, vcpu->arch.features);
>> +}
> 
> This isn't used from world-switch, could it be moved to guest.c?
yes sure.
> 
> 
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index 12529df..f7bcc60 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -1055,7 +1055,7 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
>>   }
>>   
>>   /* Read a sanitised cpufeature ID register by sys_reg_desc */
>> -static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
>> +static u64 read_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_desc const *r, bool raz)
> 
> (It might be easier on the reviewer to move these mechanical changes to an earlier patch)
Yes with including some of Dave SVE patches this wont be required.

Thanks,
Amit D
> 
> 
> Looks good,
> 
> Thanks,
> 
> James
>

Patch
diff mbox series

diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt
index a25cd21..0529a7d 100644
--- a/Documentation/arm64/pointer-authentication.txt
+++ b/Documentation/arm64/pointer-authentication.txt
@@ -82,7 +82,8 @@  pointers).
 Virtualization
 --------------
 
-Pointer authentication is not currently supported in KVM guests. KVM
-will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of
-the feature will result in an UNDEFINED exception being injected into
-the guest.
+Pointer authentication is enabled in KVM guest when virtual machine is
+created by passing a flag (KVM_ARM_VCPU_PTRAUTH) requesting this feature
+to be enabled. Without this flag, pointer authentication is not enabled
+in KVM guests and attempted use of the feature will result in an UNDEFINED
+exception being injected into the guest.
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 356156f..1e646fb 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2642,6 +2642,10 @@  Possible features:
 	  Depends on KVM_CAP_ARM_PSCI_0_2.
 	- KVM_ARM_VCPU_PMU_V3: Emulate PMUv3 for the CPU.
 	  Depends on KVM_CAP_ARM_PMU_V3.
+	- KVM_ARM_VCPU_PTRAUTH: Emulate Pointer authentication for the CPU.
+	  Depends on KVM_CAP_ARM_PTRAUTH and only on arm64 architecture. If
+	  set, then the KVM guest allows the execution of pointer authentication
+	  instructions. Otherwise, KVM treats these instructions as undefined.
 
 
 4.83 KVM_ARM_PREFERRED_TARGET
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 1bacf78..2768a53 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -43,7 +43,7 @@ 
 
 #define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
 
-#define KVM_VCPU_MAX_FEATURES 4
+#define KVM_VCPU_MAX_FEATURES 5
 
 #define KVM_REQ_SLEEP \
 	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
@@ -451,6 +451,7 @@  static inline bool kvm_arch_requires_vhe(void)
 	return false;
 }
 
+bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu);
 static inline bool kvm_supports_ptrauth(void)
 {
 	return has_vhe() && system_supports_address_auth() &&
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 97c3478..5f82ca1 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -102,6 +102,7 @@  struct kvm_regs {
 #define KVM_ARM_VCPU_EL1_32BIT		1 /* CPU running a 32bit VM */
 #define KVM_ARM_VCPU_PSCI_0_2		2 /* CPU uses PSCI v0.2 */
 #define KVM_ARM_VCPU_PMU_V3		3 /* Support guest PMUv3 */
+#define KVM_ARM_VCPU_PTRAUTH		4 /* VCPU uses address authentication */
 
 struct kvm_vcpu_init {
 	__u32 target;
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 7622ab3..d9f583b 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -179,7 +179,7 @@  static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run)
  */
 void kvm_arm_vcpu_ptrauth_trap(struct kvm_vcpu *vcpu)
 {
-	if (kvm_supports_ptrauth())
+	if (kvm_arm_vcpu_ptrauth_allowed(vcpu))
 		kvm_arm_vcpu_ptrauth_enable(vcpu);
 	else
 		kvm_inject_undefined(vcpu);
diff --git a/arch/arm64/kvm/hyp/ptrauth-sr.c b/arch/arm64/kvm/hyp/ptrauth-sr.c
index 528ee6e..6846a23 100644
--- a/arch/arm64/kvm/hyp/ptrauth-sr.c
+++ b/arch/arm64/kvm/hyp/ptrauth-sr.c
@@ -93,9 +93,23 @@  void kvm_arm_vcpu_ptrauth_reset(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpu_context *host_ctxt;
 
-	if (kvm_supports_ptrauth()) {
+	if (kvm_arm_vcpu_ptrauth_allowed(vcpu)) {
 		kvm_arm_vcpu_ptrauth_disable(vcpu);
 		host_ctxt = vcpu->arch.host_cpu_context;
 		__ptrauth_save_state(host_ctxt);
 	}
 }
+
+/**
+ * kvm_arm_vcpu_ptrauth_allowed - checks if ptrauth feature is allowed by user
+ *
+ * @vcpu: The VCPU pointer
+ *
+ * This function will be used to check userspace option to have ptrauth or not
+ * in the guest kernel.
+ */
+bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu)
+{
+	return kvm_supports_ptrauth() &&
+		test_bit(KVM_ARM_VCPU_PTRAUTH, vcpu->arch.features);
+}
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index b72a3dd..987e0c3c 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -91,6 +91,9 @@  int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_ARM_VM_IPA_SIZE:
 		r = kvm_ipa_limit;
 		break;
+	case KVM_CAP_ARM_PTRAUTH:
+		r = kvm_supports_ptrauth();
+		break;
 	default:
 		r = 0;
 	}
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 12529df..f7bcc60 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1055,7 +1055,7 @@  static bool access_cntp_cval(struct kvm_vcpu *vcpu,
 }
 
 /* Read a sanitised cpufeature ID register by sys_reg_desc */
-static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
+static u64 read_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_desc const *r, bool raz)
 {
 	u32 id = sys_reg((u32)r->Op0, (u32)r->Op1,
 			 (u32)r->CRn, (u32)r->CRm, (u32)r->Op2);
@@ -1071,7 +1071,7 @@  static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
 					 (0xfUL << ID_AA64ISAR1_API_SHIFT) |
 					 (0xfUL << ID_AA64ISAR1_GPA_SHIFT) |
 					 (0xfUL << ID_AA64ISAR1_GPI_SHIFT);
-		if (!kvm_supports_ptrauth()) {
+		if (!kvm_arm_vcpu_ptrauth_allowed(vcpu)) {
 			kvm_debug("ptrauth unsupported for guests, suppressing\n");
 			val &= ~ptrauth_mask;
 		}
@@ -1095,7 +1095,7 @@  static bool __access_id_reg(struct kvm_vcpu *vcpu,
 	if (p->is_write)
 		return write_to_read_only(vcpu, p, r);
 
-	p->regval = read_id_reg(r, raz);
+	p->regval = read_id_reg(vcpu, r, raz);
 	return true;
 }
 
@@ -1124,17 +1124,17 @@  static u64 sys_reg_to_index(const struct sys_reg_desc *reg);
  * are stored, and for set_id_reg() we don't allow the effective value
  * to be changed.
  */
-static int __get_id_reg(const struct sys_reg_desc *rd, void __user *uaddr,
-			bool raz)
+static int __get_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
+			void __user *uaddr, bool raz)
 {
 	const u64 id = sys_reg_to_index(rd);
-	const u64 val = read_id_reg(rd, raz);
+	const u64 val = read_id_reg(vcpu, rd, raz);
 
 	return reg_to_user(uaddr, &val, id);
 }
 
-static int __set_id_reg(const struct sys_reg_desc *rd, void __user *uaddr,
-			bool raz)
+static int __set_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
+			void __user *uaddr, bool raz)
 {
 	const u64 id = sys_reg_to_index(rd);
 	int err;
@@ -1145,7 +1145,7 @@  static int __set_id_reg(const struct sys_reg_desc *rd, void __user *uaddr,
 		return err;
 
 	/* This is what we mean by invariant: you can't change it. */
-	if (val != read_id_reg(rd, raz))
+	if (val != read_id_reg(vcpu, rd, raz))
 		return -EINVAL;
 
 	return 0;
@@ -1154,25 +1154,25 @@  static int __set_id_reg(const struct sys_reg_desc *rd, void __user *uaddr,
 static int get_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 		      const struct kvm_one_reg *reg, void __user *uaddr)
 {
-	return __get_id_reg(rd, uaddr, false);
+	return __get_id_reg(vcpu, rd, uaddr, false);
 }
 
 static int set_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 		      const struct kvm_one_reg *reg, void __user *uaddr)
 {
-	return __set_id_reg(rd, uaddr, false);
+	return __set_id_reg(vcpu, rd, uaddr, false);
 }
 
 static int get_raz_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 			  const struct kvm_one_reg *reg, void __user *uaddr)
 {
-	return __get_id_reg(rd, uaddr, true);
+	return __get_id_reg(vcpu, rd, uaddr, true);
 }
 
 static int set_raz_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 			  const struct kvm_one_reg *reg, void __user *uaddr)
 {
-	return __set_id_reg(rd, uaddr, true);
+	return __set_id_reg(vcpu, rd, uaddr, true);
 }
 
 /* sys_reg_desc initialiser for known cpufeature ID registers */
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 6d4ea4b..a553477 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -988,6 +988,7 @@  struct kvm_ppc_resize_hpt {
 #define KVM_CAP_ARM_VM_IPA_SIZE 165
 #define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT 166
 #define KVM_CAP_HYPERV_CPUID 167
+#define KVM_CAP_ARM_PTRAUTH 168
 
 #ifdef KVM_CAP_IRQ_ROUTING