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| author | Avi Kivity <avi@qumranet.com> | 2007-04-30 17:05:38 +0300 |
|---|---|---|
| committer | Avi Kivity <avi@qumranet.com> | 2007-07-16 12:05:38 +0300 |
| commit | a25f7e1f8c1ff68213a63dada9d5e32dc1a0f587 (patch) | |
| tree | f1c08d4c6f6736561a42dd4d9462fb97db9c75c3 /drivers/kvm | |
| parent | 05e0c8c344dd356b42e81bdf0d47d2b884bf49b5 (diff) | |
| download | blackbird-op-linux-a25f7e1f8c1ff68213a63dada9d5e32dc1a0f587.tar.gz blackbird-op-linux-a25f7e1f8c1ff68213a63dada9d5e32dc1a0f587.zip | |
KVM: Reduce misfirings of the fork detector
The kvm mmu tries to detects forks by looking for repeated writes to a
page table. If it sees a fork, it unshadows the page table so the page
table copying can proceed at native speed instead of being emulated.
However, the detector also triggered on simple demand paging access patterns:
a linear walk of memory would of course cause repeated writes to the same
pagetable page, causing it to unshadow prematurely.
Fix by resetting the fork detector if we detect a demand fault.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'drivers/kvm')
| -rw-r--r-- | drivers/kvm/paging_tmpl.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h index 73ffbffb1097..bc64cceec039 100644 --- a/drivers/kvm/paging_tmpl.h +++ b/drivers/kvm/paging_tmpl.h @@ -421,6 +421,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, pgprintk("%s: guest page fault\n", __FUNCTION__); inject_page_fault(vcpu, addr, walker.error_code); FNAME(release_walker)(&walker); + vcpu->last_pt_write_count = 0; /* reset fork detector */ return 0; } @@ -442,6 +443,9 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, FNAME(release_walker)(&walker); + if (!write_pt) + vcpu->last_pt_write_count = 0; /* reset fork detector */ + /* * mmio: emulate if accessible, otherwise its a guest fault. */ |
