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SubjectRe: [PATCH v2 11/43] arm64: kvm: Allow passing machine type in KVM creation
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On 12/04/2024 09:42, Steven Price wrote:
> Previously machine type was used purely for specifying the physical
> address size of the guest. Reserve the higher bits to specify an ARM
> specific machine type and declare a new type 'KVM_VM_TYPE_ARM_REALM'
> used to create a realm guest.
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> arch/arm64/kvm/arm.c | 17 +++++++++++++++++
> arch/arm64/kvm/mmu.c | 3 ---
> include/uapi/linux/kvm.h | 19 +++++++++++++++----
> 3 files changed, 32 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 22da6493912a..c5a6139d5454 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -173,6 +173,23 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> mutex_unlock(&kvm->lock);
> #endif
>
> + if (type & ~(KVM_VM_TYPE_ARM_MASK | KVM_VM_TYPE_ARM_IPA_SIZE_MASK))
> + return -EINVAL;
> +
> + switch (type & KVM_VM_TYPE_ARM_MASK) {
> + case KVM_VM_TYPE_ARM_NORMAL:
> + break;
> + case KVM_VM_TYPE_ARM_REALM:
> + kvm->arch.is_realm = true;
> + if (!kvm_is_realm(kvm)) {
> + /* Realm support unavailable */
> + return -EINVAL;
> + }
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> ret = kvm_share_hyp(kvm, kvm + 1);
> if (ret)
> return ret;
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index aae365647b62..af4564f3add5 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -877,9 +877,6 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
> if (kvm_is_realm(kvm))
> ipa_limit = kvm_realm_ipa_limit();
>
> - if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
> - return -EINVAL;
> -
> phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type);
> if (is_protected_kvm_enabled()) {
> phys_shift = kvm_ipa_limit;
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index a1147036d1bd..5153c837c8c7 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -635,14 +635,25 @@ struct kvm_enable_cap {
> #define KVM_S390_SIE_PAGE_OFFSET 1
>
> /*
> - * On arm64, machine type can be used to request the physical
> - * address size for the VM. Bits[7-0] are reserved for the guest
> - * PA size shift (i.e, log2(PA_Size)). For backward compatibility,
> - * value 0 implies the default IPA size, 40bits.
> + * On arm64, machine type can be used to request both the machine type and
> + * the physical address size for the VM.
> + *
> + * Bits[11-8] are reserved for the ARM specific machine type.
> + *
> + * Bits[7-0] are reserved for the guest PA size shift (i.e, log2(PA_Size)).
> + * For backward compatibility, value 0 implies the default IPA size, 40bits.
> */
> +#define KVM_VM_TYPE_ARM_SHIFT 8
> +#define KVM_VM_TYPE_ARM_MASK (0xfULL << KVM_VM_TYPE_ARM_SHIFT)
> +#define KVM_VM_TYPE_ARM(_type) \
> + (((_type) << KVM_VM_TYPE_ARM_SHIFT) & KVM_VM_TYPE_ARM_MASK)
> +#define KVM_VM_TYPE_ARM_NORMAL KVM_VM_TYPE_ARM(0)
> +#define KVM_VM_TYPE_ARM_REALM KVM_VM_TYPE_ARM(1)
> +
> #define KVM_VM_TYPE_ARM_IPA_SIZE_MASK 0xffULL
> #define KVM_VM_TYPE_ARM_IPA_SIZE(x) \
> ((x) & KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
> +
> /*
> * ioctls for /dev/kvm fds:
> */


Looks good to me.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>


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