Hello,
On 4/12/19 4:20 AM, Amit Daniel Kachhap wrote:
> This patch adds a runtime capabality for KVM tool to enable Arm64 8.3
> Pointer Authentication in guest kernel. Two vcpu features
> KVM_ARM_VCPU_PTRAUTH_[ADDRESS/GENERIC] are supplied together to enable
> Pointer Authentication in KVM guest after checking the capability.
>
> Command line options --enable-ptrauth and --disable-ptrauth are added
> to use this feature. However, if those options are not provided then
> also this feature is enabled if host supports this capability.
>
> The macros defined in the headers are not in sync and should be replaced
> from the upstream.
>
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@xxxxxxx>
> ---
> Changes since v8:
> * Added option --enable-ptrauth and --disable-ptrauth to use ptrauth. Also
> enable ptrauth if no option provided and Host supports ptrauth. [Dave Martin]
> * The macro definition are not linear as the kvmtool is not synchronised with the
> kernel changes present in kvmarm/next tree.
>
> arm/aarch32/include/kvm/kvm-cpu-arch.h | 1 +
> arm/aarch64/include/asm/kvm.h | 2 ++
> arm/aarch64/include/kvm/kvm-config-arch.h | 6 +++++-
> arm/aarch64/include/kvm/kvm-cpu-arch.h | 2 ++
> arm/include/arm-common/kvm-config-arch.h | 2 ++
> arm/kvm-cpu.c | 11 +++++++++++
> include/linux/kvm.h | 2 ++
> 7 files changed, 25 insertions(+), 1 deletion(-)
>
> diff --git a/arm/aarch32/include/kvm/kvm-cpu-arch.h b/arm/aarch32/include/kvm/kvm-cpu-arch.h
> index d28ea67..520ea76 100644
> --- a/arm/aarch32/include/kvm/kvm-cpu-arch.h
> +++ b/arm/aarch32/include/kvm/kvm-cpu-arch.h
> @@ -13,4 +13,5 @@
> #define ARM_CPU_ID 0, 0, 0
> #define ARM_CPU_ID_MPIDR 5
>
> +#define ARM_VCPU_PTRAUTH_FEATURE 0
> #endif /* KVM__KVM_CPU_ARCH_H */
> diff --git a/arm/aarch64/include/asm/kvm.h b/arm/aarch64/include/asm/kvm.h
> index 97c3478..a2546e6 100644
> --- a/arm/aarch64/include/asm/kvm.h
> +++ b/arm/aarch64/include/asm/kvm.h
> @@ -102,6 +102,8 @@ 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_ADDRESS 5 /* CPU uses address pointer authentication */
> +#define KVM_ARM_VCPU_PTRAUTH_GENERIC 6 /* CPU uses generic pointer authentication */
>
> struct kvm_vcpu_init {
> __u32 target;
> diff --git a/arm/aarch64/include/kvm/kvm-config-arch.h b/arm/aarch64/include/kvm/kvm-config-arch.h
> index 04be43d..0279b13 100644
> --- a/arm/aarch64/include/kvm/kvm-config-arch.h
> +++ b/arm/aarch64/include/kvm/kvm-config-arch.h
> @@ -8,7 +8,11 @@
> "Create PMUv3 device"), \
> OPT_U64('\0', "kaslr-seed", &(cfg)->kaslr_seed, \
> "Specify random seed for Kernel Address Space " \
> - "Layout Randomization (KASLR)"),
> + "Layout Randomization (KASLR)"), \
> + OPT_BOOLEAN('\0', "enable-ptrauth", &(cfg)->enable_ptrauth, \
> + "Enables pointer authentication"), \
> + OPT_BOOLEAN('\0', "disable-ptrauth", &(cfg)->disable_ptrauth, \
> + "Disables pointer authentication"),
>
> #include "arm-common/kvm-config-arch.h"
>
> diff --git a/arm/aarch64/include/kvm/kvm-cpu-arch.h b/arm/aarch64/include/kvm/kvm-cpu-arch.h
> index a9d8563..fcc2107 100644
> --- a/arm/aarch64/include/kvm/kvm-cpu-arch.h
> +++ b/arm/aarch64/include/kvm/kvm-cpu-arch.h
> @@ -17,4 +17,6 @@
> #define ARM_CPU_CTRL 3, 0, 1, 0
> #define ARM_CPU_CTRL_SCTLR_EL1 0
>
> +#define ARM_VCPU_PTRAUTH_FEATURE ((1UL << KVM_ARM_VCPU_PTRAUTH_ADDRESS) \
> + | (1UL << KVM_ARM_VCPU_PTRAUTH_GENERIC))
> #endif /* KVM__KVM_CPU_ARCH_H */
> diff --git a/arm/include/arm-common/kvm-config-arch.h b/arm/include/arm-common/kvm-config-arch.h
> index 5734c46..1b4287d 100644
> --- a/arm/include/arm-common/kvm-config-arch.h
> +++ b/arm/include/arm-common/kvm-config-arch.h
> @@ -10,6 +10,8 @@ struct kvm_config_arch {
> bool aarch32_guest;
> bool has_pmuv3;
> u64 kaslr_seed;
> + bool enable_ptrauth;
> + bool disable_ptrauth;
> enum irqchip_type irqchip;
> u64 fw_addr;
> };
> diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
> index 7780251..a45a649 100644
> --- a/arm/kvm-cpu.c
> +++ b/arm/kvm-cpu.c
> @@ -69,6 +69,17 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
> }
>
> /*
> + * Always enable Pointer Authentication if requested. If system supports
> + * this extension then also enable it by default provided no disable
> + * request present.
> + */
> + if ((kvm->cfg.arch.enable_ptrauth) ||
> + (kvm__supports_extension(kvm, KVM_CAP_ARM_PTRAUTH_ADDRESS) &&
> + kvm__supports_extension(kvm, KVM_CAP_ARM_PTRAUTH_GENERIC) &&
> + !kvm->cfg.arch.disable_ptrauth))
I take it that:
(1) Having both --enable-ptrauth and --disable-ptrauth present on the kvmtools
command line is allowed
(2) --enable-ptrauth takes precedence over --disable-ptrauth.
Have you considered returning an error if both are present? Having
--enable-ptrauth take precedence over --disable-ptrauth looks arbitrary to me
(my expectations would have been for --disable-ptrauth to have precendece) and
probably the user is doing something wrong if kvmtools is invoked with both
arguments.
> + vcpu_init.features[0] |= ARM_VCPU_PTRAUTH_FEATURE;
> +
> + /*
> * If the preferred target ioctl is successful then
> * use preferred target else try each and every target type
> */
> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index 6d4ea4b..de1033b 100644
> --- a/include/linux/kvm.h
> +++ b/include/linux/kvm.h
> @@ -988,6 +988,8 @@ 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_ADDRESS 169
> +#define KVM_CAP_ARM_PTRAUTH_GENERIC 170
>
> #ifdef KVM_CAP_IRQ_ROUTING
>
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