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| author | Paolo Bonzini <pbonzini@redhat.com> | 2013-09-09 13:52:33 +0200 |
|---|---|---|
| committer | Gleb Natapov <gleb@redhat.com> | 2013-09-17 12:52:31 +0300 |
| commit | ba6a3541545542721ce821d1e7e5ce35752e6fdf (patch) | |
| tree | b53ff602454f383dc8148d38d7d870972d7866db /virt/kvm | |
| parent | 3261107ebfd8f6bba57cfcdb89385779fd149a00 (diff) | |
| download | lwn-ba6a3541545542721ce821d1e7e5ce35752e6fdf.tar.gz lwn-ba6a3541545542721ce821d1e7e5ce35752e6fdf.zip | |
KVM: mmu: allow page tables to be in read-only slots
Page tables in a read-only memory slot will currently cause a triple
fault because the page walker uses gfn_to_hva and it fails on such a slot.
OVMF uses such a page table; however, real hardware seems to be fine with
that as long as the accessed/dirty bits are set. Save whether the slot
is readonly, and later check it when updating the accessed and dirty bits.
Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/kvm_main.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index bf040c4e02b3..979bff485fb0 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1058,11 +1058,15 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn) EXPORT_SYMBOL_GPL(gfn_to_hva); /* - * The hva returned by this function is only allowed to be read. - * It should pair with kvm_read_hva() or kvm_read_hva_atomic(). + * If writable is set to false, the hva returned by this function is only + * allowed to be read. */ -static unsigned long gfn_to_hva_read(struct kvm *kvm, gfn_t gfn) +unsigned long gfn_to_hva_prot(struct kvm *kvm, gfn_t gfn, bool *writable) { + struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn); + if (writable) + *writable = !memslot_is_readonly(slot); + return __gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL, false); } @@ -1430,7 +1434,7 @@ int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset, int r; unsigned long addr; - addr = gfn_to_hva_read(kvm, gfn); + addr = gfn_to_hva_prot(kvm, gfn, NULL); if (kvm_is_error_hva(addr)) return -EFAULT; r = kvm_read_hva(data, (void __user *)addr + offset, len); @@ -1468,7 +1472,7 @@ int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data, gfn_t gfn = gpa >> PAGE_SHIFT; int offset = offset_in_page(gpa); - addr = gfn_to_hva_read(kvm, gfn); + addr = gfn_to_hva_prot(kvm, gfn, NULL); if (kvm_is_error_hva(addr)) return -EFAULT; pagefault_disable(); |