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

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From: Avi Kivity
Subject: [PATCH 31/33] KVM: MMU: Flush guest tlb when reducing permissions on a pte
Date: Thursday, January 4, 2007 - 9:20 am

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@qumranet.com>

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);
+			}
 		}
 	}
 
-
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Messages in current thread:
[PATCH 0/33] KVM: MMU: Cache shadow page tables, Avi Kivity, (Thu Jan 4, 8:48 am)
[PATCH 1/33] KVM: MMU: Implement simple reverse mapping, Avi Kivity, (Thu Jan 4, 8:50 am)
[PATCH 2/33] KVM: MMU: Teach the page table walker to trac ..., Avi Kivity, (Thu Jan 4, 8:51 am)
[PATCH 3/33] KVM: MMU: Load the pae pdptrs on cr3 change l ..., Avi Kivity, (Thu Jan 4, 8:52 am)
[PATCH 4/33] KVM: MMU: Fold fetch_guest() into init_walker(), Avi Kivity, (Thu Jan 4, 8:53 am)
[PATCH 5/33] KVM: MU: Special treatment for shadow pae roo ..., Avi Kivity, (Thu Jan 4, 8:54 am)
[PATCH 6/33] KVM: MMU: Use the guest pdptrs instead of map ..., Avi Kivity, (Thu Jan 4, 8:55 am)
[PATCH 7/33] KVM: MMU: Make the shadow page tables also sp ..., Avi Kivity, (Thu Jan 4, 8:56 am)
[PATCH 8/33] KVM: MMU: Make kvm_mmu_alloc_page() return a ..., Avi Kivity, (Thu Jan 4, 8:57 am)
[PATCH 9/33] KVM: MMU: Shadow page table caching, Avi Kivity, (Thu Jan 4, 8:58 am)
[PATCH 10/33] KVM: MMU: Write protect guest pages when a s ..., Avi Kivity, (Thu Jan 4, 8:59 am)
[PATCH 11/33] KVM: MMU: Let the walker extract the target ..., Avi Kivity, (Thu Jan 4, 9:00 am)
[PATCH 12/33] KVM: MMU: Support emulated writes into RAM, Avi Kivity, (Thu Jan 4, 9:01 am)
[PATCH 13/33] KVM: MMU: Zap shadow page table entries on w ..., Avi Kivity, (Thu Jan 4, 9:02 am)
[PATCH 14/33] KVM: MMU: If emulating an instruction fails, ..., Avi Kivity, (Thu Jan 4, 9:03 am)
[PATCH 15/33] KVM: MMU: Implement child shadow unlinking, Avi Kivity, (Thu Jan 4, 9:04 am)
[PATCH 16/33] KVM: MMU: kvm_mmu_put_page() only removes on ..., Avi Kivity, (Thu Jan 4, 9:05 am)
[PATCH 17/33] KVM: MMU: oom handling, Avi Kivity, (Thu Jan 4, 9:06 am)
[PATCH 18/33] KVM: MMU: Remove invlpg interception, Avi Kivity, (Thu Jan 4, 9:07 am)
[PATCH 19/33] KVM: MMU: Remove release_pt_page_64(), Avi Kivity, (Thu Jan 4, 9:08 am)
[PATCH 20/33] KVM: MMU: Handle misaligned accesses to writ ..., Avi Kivity, (Thu Jan 4, 9:09 am)
[PATCH 21/33] KVM: MMU: &lt;ove is_empty_shadow_page() above ..., Avi Kivity, (Thu Jan 4, 9:10 am)
[PATCH 22/33] KVM: MMU: Ensure freed shadow pages are clean, Avi Kivity, (Thu Jan 4, 9:11 am)
[PATCH 23/33] KVM: MMU: If an empty shadow page is not emp ..., Avi Kivity, (Thu Jan 4, 9:12 am)
[PATCH 24/33] KVM: MMU: Page table write flood protection, Avi Kivity, (Thu Jan 4, 9:13 am)
[PATCH 25/33] KVM: MMU: Never free a shadow page actively ..., Avi Kivity, (Thu Jan 4, 9:14 am)
[PATCH 26/33] KVM: MMU: Fix cmpxchg8b emulation, Avi Kivity, (Thu Jan 4, 9:15 am)
[PATCH 27/33] KVM: MMU: Treat user-mode faults as a hint t ..., Avi Kivity, (Thu Jan 4, 9:16 am)
[PATCH 28/33] KVM: MMU: Free pages on kvm destruction, Avi Kivity, (Thu Jan 4, 9:17 am)
[PATCH 29/33] KVM: MMU: Replace atomic allocations by prea ..., Avi Kivity, (Thu Jan 4, 9:18 am)
[PATCH 30/33] KVM: MMU: Detect oom conditions and propagat ..., Avi Kivity, (Thu Jan 4, 9:19 am)
[PATCH 31/33] KVM: MMU: Flush guest tlb when reducing perm ..., Avi Kivity, (Thu Jan 4, 9:20 am)
[PATCH 32/33] KVM: MMU: Destroy mmu while we still have a ..., Avi Kivity, (Thu Jan 4, 9:21 am)
[PATCH 33/33] KVM: MMU: add audit code to check mappings, ..., Avi Kivity, (Thu Jan 4, 9:22 am)
Re: [PATCH 0/33] KVM: MMU: Cache shadow page tables, Andrew Morton, (Thu Jan 4, 10:22 am)
Re: [PATCH 0/33] KVM: MMU: Cache shadow page tables, Avi Kivity, (Thu Jan 4, 10:41 am)
Re: [PATCH 0/33] KVM: MMU: Cache shadow page tables, Ingo Molnar, (Thu Jan 4, 11:02 am)