cccf748b81
The kvm mmio read path looks like: 1. guest read faults 2. kvm emulates read, calls emulator_read_emulated() 3. fails as a read requires userspace help 4. exit to userspace 5. userspace emulates read, kvm sets vcpu->mmio_read_completed 6. re-enter guest, fault again 7. kvm emulates read, calls emulator_read_emulated() 8. succeeds as vcpu->mmio_read_emulated is set 9. instruction completes and guest is resumed A problem surfaces if the userspace exit (step 5) also requests an interrupt injection. In that case, the guest does not re-execute the original instruction, but the interrupt handler. The next time an mmio read is exectued (likely for a different address), step 3 will find vcpu->mmio_read_completed set and return the value read for the original instruction. The problem manifested itself in a few annoying ways: - little squares appear randomly on console when switching virtual terminals - ne2000 fails under nfs read load - rtl8139 complains about "pci errors" even though the device model is incapable of issuing them. Fix by skipping interrupt injection if an mmio read is pending. A better fix is to avoid re-entry into the guest, and re-emulating immediately instead. However that's a bit more complex. 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> |
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| .. | ||
| Kconfig | ||
| kvm.h | ||
| kvm_main.c | ||
| kvm_svm.h | ||
| kvm_vmx.h | ||
| Makefile | ||
| mmu.c | ||
| paging_tmpl.h | ||
| segment_descriptor.h | ||
| svm.c | ||
| svm.h | ||
| vmx.c | ||
| vmx.h | ||
| x86_emulate.c | ||
| x86_emulate.h | ||