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| author | Avi Kivity <avi@qumranet.com> | 2007-01-22 20:40:40 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-01-23 07:52:06 -0800 |
| commit | fc3dffe12148b9612870eb21b24f2aecefa9ea24 (patch) | |
| tree | 67a7671e73e5e962355885ffa7a25821c27247e7 /drivers/kvm/paging_tmpl.h | |
| parent | 038e51de2e7ae2c8e9d8a0b15231f8509875dc33 (diff) | |
| download | blackbird-op-linux-fc3dffe12148b9612870eb21b24f2aecefa9ea24.tar.gz blackbird-op-linux-fc3dffe12148b9612870eb21b24f2aecefa9ea24.zip | |
[PATCH] KVM: fix bogus pagefault on writable pages
If a page is marked as dirty in the guest pte, set_pte_common() can set the
writable bit on newly-instantiated shadow pte. This optimization avoids
a write fault after the initial read fault.
However, if a write fault instantiates the pte, fix_write_pf() incorrectly
reports the fault as a guest page fault, and the guest oopses on what appears
to be a correctly-mapped page.
Fix is to detect the condition and only report a guest page fault on a user
access to a kernel page.
With the fix, a kvm guest can survive a whole night of running the kernel
hacker's screensaver (make -j9 in a loop).
Signed-off-by: Avi Kivity <avi@qumranet.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/kvm/paging_tmpl.h')
| -rw-r--r-- | drivers/kvm/paging_tmpl.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h index 2dbf4307ed9e..6bc41950fbb3 100644 --- a/drivers/kvm/paging_tmpl.h +++ b/drivers/kvm/paging_tmpl.h @@ -274,7 +274,7 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page; if (is_writeble_pte(*shadow_ent)) - return 0; + return !user || (*shadow_ent & PT_USER_MASK); writable_shadow = *shadow_ent & PT_SHADOW_WRITABLE_MASK; if (user) { |
