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authorPaolo Bonzini <pbonzini@redhat.com>2013-09-09 13:52:33 +0200
committerGleb Natapov <gleb@redhat.com>2013-09-17 12:52:31 +0300
commitba6a3541545542721ce821d1e7e5ce35752e6fdf (patch)
treeb53ff602454f383dc8148d38d7d870972d7866db /virt
parent3261107ebfd8f6bba57cfcdb89385779fd149a00 (diff)
downloadlinux-ba6a3541545542721ce821d1e7e5ce35752e6fdf.tar.gz
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')
-rw-r--r--virt/kvm/kvm_main.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index bf040c4e02b..979bff485fb 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();