mirror of
https://github.com/torvalds/linux.git
synced 2024-11-07 12:41:55 +00:00
d4b06c2d4c
The kvm i8254 emulation for counter 0 (but not for counters 1 and 2) has at least two bugs in mode 0: 1. The OUT bit, computed by pit_get_out(), is never set high. 2. The counter value, computed by pit_get_count(), wraps back around to the initial counter value, rather than wrapping back to 0xFFFF (which is the behavior described in the comment in __kpit_elapsed, the behavior implemented by qemu, and the behavior observed on AMD hardware). The bug stems from __kpit_elapsed computing the elapsed time mod the initial counter value (stored as nanoseconds in ps->period). This is both unnecessary (none of the callers of kpit_elapsed expect the value to be at most the initial counter value) and incorrect (it causes pit_get_count to appear to wrap around to the initial counter value rather than 0xFFFF). Removing this mod from __kpit_elapsed fixes both of the above bugs. Signed-off-by: Nickolai Zeldovich <nickolai@csail.mit.edu> Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> |
||
|---|---|---|
| .. | ||
| cpuid.c | ||
| cpuid.h | ||
| emulate.c | ||
| i8254.c | ||
| i8254.h | ||
| i8259.c | ||
| irq.c | ||
| irq.h | ||
| Kconfig | ||
| kvm_cache_regs.h | ||
| lapic.c | ||
| lapic.h | ||
| Makefile | ||
| mmu_audit.c | ||
| mmu.c | ||
| mmu.h | ||
| mmutrace.h | ||
| paging_tmpl.h | ||
| pmu.c | ||
| svm.c | ||
| trace.h | ||
| tss.h | ||
| vmx.c | ||
| x86.c | ||
| x86.h | ||