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KVM: x86/mmu: Handle guest page faults for guest_memfd with shared memory

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Update the KVM MMU fault handler to service guest page faults
for memory slots backed by guest_memfd with mmap support. For such
slots, the MMU must always fault in pages directly from guest_memfd,
bypassing the host's userspace_addr.

This ensures that guest_memfd-backed memory is always handled through
the guest_memfd specific faulting path, regardless of whether it's for
private or non-private (shared) use cases.

Additionally, rename kvm_mmu_faultin_pfn_private() to
kvm_mmu_faultin_pfn_gmem(), as this function is now used to fault in
pages from guest_memfd for both private and non-private memory,
accommodating the new use cases.

Co-developed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Co-developed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
[sean: drop the helper]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-ID: <20250729225455.670324-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ackerley Tng 2025-07-29 15:54:47 -07:00 committed by Paolo Bonzini
parent b7d97f69ed
commit f029f04ddb
1 changed files with 4 additions and 4 deletions
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8
arch/x86/kvm/mmu/mmu.c
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@ -4561,8 +4561,8 @@ static void kvm_mmu_finish_page_fault(struct kvm_vcpu *vcpu,
r == RET_PF_RETRY, fault->map_writable);
}
static int kvm_mmu_faultin_pfn_private(struct kvm_vcpu *vcpu,
struct kvm_page_fault *fault)
static int kvm_mmu_faultin_pfn_gmem(struct kvm_vcpu *vcpu,
struct kvm_page_fault *fault)
{
int max_order, r;
@ -4589,8 +4589,8 @@ static int __kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu,
{
unsigned int foll = fault->write ? FOLL_WRITE : 0;
if (fault->is_private)
return kvm_mmu_faultin_pfn_private(vcpu, fault);
if (fault->is_private || kvm_memslot_is_gmem_only(fault->slot))
return kvm_mmu_faultin_pfn_gmem(vcpu, fault);
foll |= FOLL_NOWAIT;
fault->pfn = __kvm_faultin_pfn(fault->slot, fault->gfn, foll,