The patch titled
KVM: fix bogus pagefault on writable pages
has been removed from the -mm tree. Its filename was
kvm-fix-bogus-pagefault-on-writable-pages.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: KVM: fix bogus pagefault on writable pages
From: Avi Kivity <avi@xxxxxxxxxxxx>
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@xxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/kvm/paging_tmpl.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN drivers/kvm/paging_tmpl.h~kvm-fix-bogus-pagefault-on-writable-pages drivers/kvm/paging_tmpl.h
--- a/drivers/kvm/paging_tmpl.h~kvm-fix-bogus-pagefault-on-writable-pages
+++ a/drivers/kvm/paging_tmpl.h
@@ -274,7 +274,7 @@ static int FNAME(fix_write_pf)(struct kv
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) {
_
Patches currently in -mm which might be from avi@xxxxxxxxxxxx are
kvm-svm-fix-svm-idt-confusion.patch
kvm-emulate-ia32_misc_enable-msr.patch
kvm-mmu-perform-access-checks-in-walk_addr.patch
kvm-mmu-report-nx-faults-to-the-guest.patch
kvm-svm-propagate-cpu-shutdown-events-to-userspace.patch
fix-config_x86_64_-typo-in-drivers-kvm-svmc.patch
fix-x86_64-mm-convert-i386-pda-code-to-use-%fs.patch
-
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