KVM x86 fixes for 6.18: - Expand the KVM_PRE_FAULT_MEMORY selftest to add a regression test for the bug fixed by commit 3ccbf6f47098 ("KVM: x86/mmu: Return -EAGAIN if userspace deletes/moves memslot during prefault") - Don't try to get PMU capabbilities from perf when running a CPU with hybrid CPUs/PMUs, as perf will rightly WARN. - Rework KVM_CAP_GUEST_MEMFD_MMAP (newly introduced in 6.18) into a more generic KVM_CAP_GUEST_MEMFD_FLAGS - Add a guest_memfd INIT_SHARED flag and require userspace to explicitly set said flag to initialize memory as SHARED, irrespective of MMAP. The behavior merged in 6.18 is that enabling mmap() implicitly initializes memory as SHARED, which would result in an ABI collision for x86 CoCo VMs as their memory is currently always initialized PRIVATE. - Allow mmap() on guest_memfd for x86 CoCo VMs, i.e. on VMs with private memory, to enable testing such setups, i.e. to hopefully flush out any other lurking ABI issues before 6.18 is officially released. - Add testcases to the guest_memfd selftest to cover guest_memfd without MMAP, and host userspace accesses to mmap()'d private memory.
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| @@ -729,7 +729,17 @@ static inline bool kvm_arch_has_private_mem(struct kvm *kvm) · 728 unmodified lines | ||
| 729 | 729 | #endif |
| 730 | 730 | |
| 731 | 731 | #ifdef CONFIG_KVM_GUEST_MEMFD |
| 732 | −bool kvm_arch_supports_gmem_mmap(struct kvm *kvm); | |
| 732 | +bool kvm_arch_supports_gmem_init_shared(struct kvm *kvm); | |
| 733 | + | |
| 734 | +static inline u64 kvm_gmem_get_supported_flags(struct kvm *kvm) | |
| 735 | +{ | |
| 736 | + u64 flags = GUEST_MEMFD_FLAG_MMAP; | |
| 737 | + | |
| 738 | + if (!kvm || kvm_arch_supports_gmem_init_shared(kvm)) | |
| 739 | + flags |= GUEST_MEMFD_FLAG_INIT_SHARED; | |
| 740 | + | |
| 741 | + return flags; | |
| 742 | +} | |
| 733 | 743 | #endif |
| 734 | 744 | |
| 735 | 745 | #ifndef kvm_arch_has_readonly_mem |