diff options
author | Sean Christopherson <seanjc@google.com> | 2023-07-29 04:35:29 +0300 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-08-31 21:08:14 +0300 |
commit | 338068b5bec4dfa11cf50eb8c1839d1e27749395 (patch) | |
tree | cdf1fda2ffdc3f526268b965ebb1f2451e79ee7c /arch/x86/include/asm/kvm_page_track.h | |
parent | e998fb1a30131fdc7c734bc7422000b41146b631 (diff) | |
download | linux-338068b5bec4dfa11cf50eb8c1839d1e27749395.tar.xz |
KVM: x86/mmu: Drop infrastructure for multiple page-track modes
Drop "support" for multiple page-track modes, as there is no evidence
that array-based and refcounted metadata is the optimal solution for
other modes, nor is there any evidence that other use cases, e.g. for
access-tracking, will be a good fit for the page-track machinery in
general.
E.g. one potential use case of access-tracking would be to prevent guest
access to poisoned memory (from the guest's perspective). In that case,
the number of poisoned pages is likely to be a very small percentage of
the guest memory, and there is no need to reference count the number of
access-tracking users, i.e. expanding gfn_track[] for a new mode would be
grossly inefficient. And for poisoned memory, host userspace would also
likely want to trap accesses, e.g. to inject #MC into the guest, and that
isn't currently supported by the page-track framework.
A better alternative for that poisoned page use case is likely a
variation of the proposed per-gfn attributes overlay (linked), which
would allow efficiently tracking the sparse set of poisoned pages, and by
default would exit to userspace on access.
Link: https://lore.kernel.org/all/Y2WB48kD0J4VGynX@google.com
Cc: Ben Gardon <bgardon@google.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-24-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/include/asm/kvm_page_track.h')
-rw-r--r-- | arch/x86/include/asm/kvm_page_track.h | 11 |
1 files changed, 2 insertions, 9 deletions
diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h index 61adb07b5927..9e4ee26d1779 100644 --- a/arch/x86/include/asm/kvm_page_track.h +++ b/arch/x86/include/asm/kvm_page_track.h @@ -4,17 +4,10 @@ #include <linux/kvm_types.h> -enum kvm_page_track_mode { - KVM_PAGE_TRACK_WRITE, - KVM_PAGE_TRACK_MAX, -}; - void kvm_slot_page_track_add_page(struct kvm *kvm, - struct kvm_memory_slot *slot, gfn_t gfn, - enum kvm_page_track_mode mode); + struct kvm_memory_slot *slot, gfn_t gfn); void kvm_slot_page_track_remove_page(struct kvm *kvm, - struct kvm_memory_slot *slot, gfn_t gfn, - enum kvm_page_track_mode mode); + struct kvm_memory_slot *slot, gfn_t gfn); #ifdef CONFIG_KVM_EXTERNAL_WRITE_TRACKING /* |