Merge tag 'renesas-soc-for-v3.13' of git://git.kernel.org/pub/scm/linux/kernel/git...

[firefly-linux-kernel-4.4.55.git] / arch / x86 / kvm / paging_tmpl.h

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 04333015917984a6b65f3fd0ab4ecbad2f5b1f2a..ad75d77999d085037469539d42a5df140533971d 100644 (file)
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -99,6 +99,7 @@ struct guest_walker {
        pt_element_t prefetch_ptes[PTE_PREFETCH_NUM];
        gpa_t pte_gpa[PT_MAX_FULL_LEVELS];
        pt_element_t __user *ptep_user[PT_MAX_FULL_LEVELS];
+       bool pte_writable[PT_MAX_FULL_LEVELS];
        unsigned pt_access;
        unsigned pte_access;
        gfn_t gfn;
@@ -235,6 +236,22 @@ static int FNAME(update_accessed_dirty_bits)(struct kvm_vcpu *vcpu,
                if (pte == orig_pte)
                        continue;
 
+               /*
+                * If the slot is read-only, simply do not process the accessed
+                * and dirty bits.  This is the correct thing to do if the slot
+                * is ROM, and page tables in read-as-ROM/write-as-MMIO slots
+                * are only supported if the accessed and dirty bits are already
+                * set in the ROM (so that MMIO writes are never needed).
+                *
+                * Note that NPT does not allow this at all and faults, since
+                * it always wants nested page table entries for the guest
+                * page tables to be writable.  And EPT works but will simply
+                * overwrite the read-only memory to set the accessed and dirty
+                * bits.
+                */
+               if (unlikely(!walker->pte_writable[level - 1]))
+                       continue;
+
                ret = FNAME(cmpxchg_gpte)(vcpu, mmu, ptep_user, index, orig_pte, pte);
                if (ret)
                        return ret;
@@ -309,7 +326,8 @@ retry_walk:
                        goto error;
                real_gfn = gpa_to_gfn(real_gfn);
 
-               host_addr = gfn_to_hva(vcpu->kvm, real_gfn);
+               host_addr = gfn_to_hva_prot(vcpu->kvm, real_gfn,
+                                           &walker->pte_writable[walker->level - 1]);
                if (unlikely(kvm_is_error_hva(host_addr)))
                        goto error;