On Wed, Dec 14, 2022 at 01:39:54PM -0600, Michael Roth wrote:
> This mainly indicates to KVM that it should expect all private guest
> memory to be backed by private memslots. Ideally this would work
> similarly for others archs, give or take a few additional flags, but
> for now it's a simple boolean indicator for x86.
>
> Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 3 +++
> arch/x86/kvm/x86.c | 10 ++++++++++
> include/uapi/linux/kvm.h | 1 +
> 3 files changed, 14 insertions(+)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 27ef31133352..2b6244525107 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1438,6 +1438,9 @@ struct kvm_arch {
> */
> #define SPLIT_DESC_CACHE_MIN_NR_OBJECTS (SPTE_ENT_PER_PAGE + 1)
> struct kvm_mmu_memory_cache split_desc_cache;
> +
> + /* Use/enforce unmapped private memory. */
> + bool upm_mode;
> };
>
> struct kvm_vm_stat {
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c67e22f3e2ee..99ecf99bc4d2 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4421,6 +4421,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> case KVM_CAP_EXIT_HYPERCALL:
> r = KVM_EXIT_HYPERCALL_VALID_MASK;
> break;
> +#ifdef CONFIG_HAVE_KVM_MEMORY_ATTRIBUTES
> + case KVM_CAP_UNMAPPED_PRIVATE_MEM:
> + r = 1;
> + break;
> +#endif
> case KVM_CAP_SET_GUEST_DEBUG2:
> return KVM_GUESTDBG_VALID_MASK;
> #ifdef CONFIG_KVM_XEN
> @@ -6382,6 +6387,10 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
> }
> mutex_unlock(&kvm->lock);
> break;
> + case KVM_CAP_UNMAPPED_PRIVATE_MEM:
> + kvm->arch.upm_mode = true;
> + r = 0;
> + break;
> default:
> r = -EINVAL;
> break;
> @@ -12128,6 +12137,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> kvm->arch.default_tsc_khz = max_tsc_khz ? : tsc_khz;
> kvm->arch.guest_can_read_msr_platform_info = true;
> kvm->arch.enable_pmu = enable_pmu;
> + kvm->arch.upm_mode = false;
>
> #if IS_ENABLED(CONFIG_HYPERV)
> spin_lock_init(&kvm->arch.hv_root_tdp_lock);
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index c7e9d375a902..cc9424ccf9b2 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1219,6 +1219,7 @@ struct kvm_ppc_resize_hpt {
> #define KVM_CAP_DIRTY_LOG_RING_ACQ_REL 223
> #define KVM_CAP_S390_PROTECTED_ASYNC_DISABLE 224
> #define KVM_CAP_MEMORY_ATTRIBUTES 225
> +#define KVM_CAP_UNMAPPED_PRIVATE_MEM 240
>
> #ifdef KVM_CAP_IRQ_ROUTING
>
> --
> 2.25.1
>
Why we want to carry non-UPM support still?
BR, Jarkko
