Add CAP to enumerate supported SET_MEMORY_ATTRIBUTES2 flags, so userspace can find out which flags are supported when sending the KVM_SET_MEMORY_ATTRIBUTES2 ioctl to a guest_memfd.
These flags are only supported by guest_memfd, hence, if vm_memory_attributes is enabled, return 0 - no flags are supported when KVM_SET_MEMORY_ATTRIBUTES2 is sent to a VM fd. Signed-off-by: Ackerley Tng <[email protected]> --- Documentation/virt/kvm/api.rst | 3 +++ include/linux/kvm_host.h | 12 ++++++++++++ include/uapi/linux/kvm.h | 1 + virt/kvm/kvm_main.c | 5 +++++ 4 files changed, 21 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 90587a9c09d3f..73101d6e649b7 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6680,6 +6680,9 @@ guarantees are made on offset ranges that do not have memory allocated and range [0x0000, 0x3000) was set to shared, the content mode would apply to only to offset ranges [0x0000, 0x1000) and [0x2000, 0x3000). +The supported content modes can be queried using +``KVM_CAP_MEMORY_ATTRIBUTES2_FLAGS``. + See also: :ref: `KVM_SET_MEMORY_ATTRIBUTES`. .. _kvm_run: diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 4ba3c4b303f4a..d671c9795dfce 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -2536,6 +2536,18 @@ static inline u64 kvm_supported_mem_attributes(struct kvm *kvm) return 0; } +static inline u64 kvm_supported_set_mem_attributes2_flags(struct kvm *kvm) +{ + if (!IS_ENABLED(CONFIG_KVM_GUEST_MEMFD)) + return 0; + + if (!kvm) + return KVM_SET_MEMORY_ATTRIBUTES2_ZERO | + KVM_SET_MEMORY_ATTRIBUTES2_PRESERVE; + + return kvm_arch_gmem_supported_content_modes(kvm); +} + typedef unsigned long (kvm_get_memory_attributes_t)(struct kvm *kvm, gfn_t gfn); DECLARE_STATIC_CALL(__kvm_get_memory_attributes, kvm_get_memory_attributes_t); diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 0fc9ad4ea0d93..4d1e09d022c48 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -991,6 +991,7 @@ struct kvm_enable_cap { #define KVM_CAP_S390_KEYOP 247 #define KVM_CAP_MEMORY_ATTRIBUTES2 248 #define KVM_CAP_GUEST_MEMFD_MEMORY_ATTRIBUTES 249 +#define KVM_CAP_MEMORY_ATTRIBUTES2_FLAGS 250 struct kvm_irq_routing_irqchip { __u32 irqchip; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 85c14197587d4..6607127eaaeed 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4980,6 +4980,11 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) return 0; return kvm_supported_mem_attributes(kvm); + case KVM_CAP_MEMORY_ATTRIBUTES2_FLAGS: + if (vm_memory_attributes) + return 0; + + return kvm_supported_set_mem_attributes2_flags(kvm); #endif default: break; -- 2.53.0.1018.g2bb0e51243-goog
