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charset="US-ASCII"; x-default=true X-Rspamd-Server: rspam02 X-Rspam-User: X-Stat-Signature: j6ruwhh1j83hqmkjmrfzpfcub1cs1cfp X-Rspamd-Queue-Id: A4D8E2000C X-HE-Tag: 1785845158-191839 X-HE-Meta: U2FsdGVkX1/QUp8NnWKx6ORkt1seyLD+ZnuIDomdAsCzjjJYEVLPcRGQlN1hjI5TinvGPcg/uUXJvpjnq4uOPMPpeBW4t2KsgbOqnU8T5/tUkniZH79E7HBfVBFM7jcRB6zGboxzJlRGL0thQV88iP65t04GsCHbHOpYbtCnZtu8CB0XscMdnVp+Vus/OEfQ8R+c7Cfo8HRxPqtictrh3+aVYuXKp+iJP4HMoi0Ig6eM12npDwiegoVJcXJLlUez35w93ocjo/yVhWQGxWYah6qzy4vE+/Su2+sv6uBzw2BNQZN5CTzpR4cqlcIJNgzJ6MJHzdZkmo0UsKVDJAl0ruRL4DHaQZ+g2MUUstYatf9LIgxRXTpZ0xLUd1M8XQHJBUI7qBbSqcL3wZgqrd0s33UF90XJ4TSaXt/vWoOxh82O4VQVCModE0pQwvDqyBvTA7celA1ECOfOH7X0jHPSOEKYJmE61gQPAYGt6cV0yLkXrob3WmR0ly/WG6/Fu+8juoGWFKVP+6DfuqaHoGaKBqd1Ter7WSoqDQaj3pfBBu+YKHL3mXsZ8sV8oPezjh86RsRHaBJBFTUx9EAJx0zLUHQPOjKS23PblnW6ibMEauMpnvkpGIG0/3Mn/2/rgpaQT/MUyAwsxQiXzy6+jus/SqToXk3g62bU+UvtPQGIhXLvSrrospII06FaBNgCM0LpNWFsI0ZYxSokcigAaQ2sFLi4TPspcEpNRqvsjSvJwecF7+9/LAAfF8GnYkCFLcv68eA1ocYHUc4rFwlIeg789XRDvrv1EhUj1EVXftyImG3NeVEa1yEX7U7cFLrcv7n0vXh79NQl3t9IBe9tBkpFrMFfJoX42+pZW5DCwi9lM6ap6lIYveIaw4IJyEaYindge1H5KhF+HbER08t5jR4QJch56yHmBwaBRbBdcdyUdfUSfa1za8YcNVTRmqDvSrb/BK9iTnX/cPa+7YBu2cZ 34cg3lSM RQ3zAATC+B2+Pi1YZdcU4DLVP+yCP9eugk7vOf0UtTH29CK/iJgjIz7TOV0f7DsaM4QNVmfUCJxvy2EbvN1dtf2w4GeEoPWjwQKEgp8xJMw22nnQvuFBmuS5zlFy0Cp4WisHZekLvojjwJLTteO1FS1tPcj241BUt6J1oOvep6SFa/XFK9ypV5XUvDUOBkoOPDsmJoY5idDC54ZFgTegrxsfkf35ykQrJexLjIvBIeFXWWr6QLTZtRqyKK20m3PUUq1xLkIE4W1wpyRmmYBF20GoTKNCQuQvdDMy+YdbCY9BiNAQzhhxJBNb03K353WzudUXW/qj5tYxBMEwAMjr3vfG4HJ7TnDA1Kx42tIwmCND5S8hQwvqffG6jnAtx/70Gh8RVK2cRS23qz1YIPRhXRbKJaAEw98+lQiySp6kPvLCU/1HDyVlCLEEpCA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: KVM's behavior when the guest writes to a non-writable VMA is inconsistent. For regular, page-backed mappings it returns KVM_PFN_ERR_FAULT and thus returns -EFAULT to userspace (which is ABI, and relied upon by tests); for VM_IO/VM_PFNMAP mappings instead it returns KVM_PFN_ERR_RO_FAULT and thus exits to userspace with KVM_EXIT_MMIO. This behavior for VM_{IO,PFNMAP} was added by commit bd2fae8da794 ("KVM: do not assume PTE is writable after follow_pfn"), and even if it has been in place for five years it is unlikely that it is relied upon by userspace, since it is inconsistent with KVM itself. Change hva_to_pfn() to return KVM_PFN_ERR_FAULT for all non-writable VMAs, and restrict KVM_EXIT_MMIO to the case of an explicitly read-only memslot. Suggested-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index b7c21a48a45c..da5b0bb62590 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2999,15 +2999,10 @@ kvm_pfn_t hva_to_pfn(struct kvm_follow_pfn *kfp) * or the page might be absent. */ - if (vma == NULL || unlikely(!(vma->vm_flags & VM_READ))) { + if (vma == NULL || + unlikely(!(vma->vm_flags & VM_READ)) || + ((kfp->flags & FOLL_WRITE) && unlikely(!(vma->vm_flags & VM_WRITE)))) { pfn = KVM_PFN_ERR_FAULT; - } else if ((kfp->flags & FOLL_WRITE) && unlikely(!(vma->vm_flags & VM_WRITE))) { - /* - * Exit to userspace for PROT_READ mappings in a writable - * memslot, as this is part of the API. - */ - pfn = vma->vm_flags & (VM_IO | VM_PFNMAP) ? KVM_PFN_ERR_RO_FAULT : - KVM_PFN_ERR_FAULT; } else if (vma->vm_flags & (VM_IO | VM_PFNMAP)) { r = hva_to_pfn_remapped(vma, kfp, &pfn); if (r == -EAGAIN) -- 2.55.0