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ddc16abbba
When creating a new upper-level shadow page, zap unsync shadow pages at
the same target gfn instead of attempting to sync the pages. This fixes
a bug where an unsync shadow page could be sync'd with an incompatible
context, e.g. wrong smm, is_guest, etc... flags. In practice, the bug is
relatively benign as sync_page() is all but guaranteed to fail its check
that the guest's desired gfn (for the to-be-sync'd page) matches the
current gfn associated with the shadow page. I.e. kvm_sync_page() would
end up zapping the page anyways.
Alternatively, __kvm_sync_page() could be modified to explicitly verify
the mmu_role of the unsync shadow page is compatible with the current MMU
context. But, except for this specific case, __kvm_sync_page() is called
iff the page is compatible, e.g. the transient sync in kvm_mmu_get_page()
requires an exact role match, and the call from kvm_sync_mmu_roots() is
only synchronizing shadow pages from the current MMU (which better be
compatible or KVM has problems). And as described above, attempting to
sync shadow pages when creating an upper-level shadow page is unlikely
to succeed, e.g. zero successful syncs were observed when running Linux
guests despite over a million attempts.
Fixes:
|
||
|---|---|---|
| .. | ||
| mmu | ||
| svm | ||
| vmx | ||
| cpuid.c | ||
| cpuid.h | ||
| debugfs.c | ||
| emulate.c | ||
| fpu.h | ||
| hyperv.c | ||
| hyperv.h | ||
| i8254.c | ||
| i8254.h | ||
| i8259.c | ||
| ioapic.c | ||
| ioapic.h | ||
| irq_comm.c | ||
| irq.c | ||
| irq.h | ||
| Kconfig | ||
| kvm_cache_regs.h | ||
| kvm_emulate.h | ||
| kvm_onhyperv.c | ||
| kvm_onhyperv.h | ||
| lapic.c | ||
| lapic.h | ||
| Makefile | ||
| mmu.h | ||
| mtrr.c | ||
| pmu.c | ||
| pmu.h | ||
| reverse_cpuid.h | ||
| trace.h | ||
| tss.h | ||
| x86.c | ||
| x86.h | ||
| xen.c | ||
| xen.h | ||