[PATCH 31/33] KVM: MMU: Flush guest tlb when reducing permissions on a pte

Avi Kivity
2007-01-04T16:20:07Z

If we reduce permissions on a pte, we must flush the cached copy of the pte
from the guest's tlb.

This is implemented at the moment by flushing the entire guest tlb, and can
be improved by flushing just the relevant virtual address, if it is known.

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/mmu.c
===================================================================
--- linux-2.6.orig/drivers/kvm/mmu.c
+++ linux-2.6/drivers/kvm/mmu.c
@@ -383,6 +383,7 @@ static void rmap_write_protect(struct kv
BUG_ON(!(*spte & PT_WRITABLE_MASK));
rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
rmap_remove(vcpu, spte);
+ kvm_arch_ops->tlb_flush(vcpu);
*spte &= ~(u64)PT_WRITABLE_MASK;
}
}
@@ -594,6 +595,7 @@ static void kvm_mmu_page_unlink_children
rmap_remove(vcpu, &pt[i]);
pt[i] = 0;
}
+ kvm_arch_ops->tlb_flush(vcpu);
return;
}

@@ -927,7 +929,10 @@ static inline void set_pte_common(struct
pgprintk("%s: found shadow page for %lx, marking ro\n",
__FUNCTION__, gfn);
access_bits &= ~PT_WRITABLE_MASK;
- *shadow_pte &= ~PT_WRITABLE_MASK;
+ if (is_writeble_pte(*shadow_pte)) {
+ *shadow_pte &= ~PT_WRITABLE_MASK;
+ kvm_arch_ops->tlb_flush(vcpu);