Messages in this thread | | | Subject | Re: [PATCH v3 01/10] KVM: MMU: fix decoding cache type from MTRR | From | Paolo Bonzini <> | Date | Mon, 13 Jul 2015 17:13:00 +0200 |
| |
On 13/07/2015 16:45, Xiao Guangrong wrote: >> + /* MTRR is completely disabled, use UC for all of physical >> memory. */ >> + if (!(mtrr_state->enabled & 0x2)) >> + return MTRR_TYPE_UNCACHABLE; >> >> actually disappears in commit fa61213746a7 (KVM: MTRR: simplify >> kvm_mtrr_get_guest_memory_type, 2015-06-15). > > :( > > Based on the SDM, UC is applied to all memory rather than default-type > if MTRR is disabled.
There are two issues I think. One is that I cannot find in the current code that "UC is applied to all memory rather than default-type if MTRR is disabled". mtrr_default_type unconditionally looks at mtrr_state->deftype.
> However, fast boot came back if "return 0xFF" here. So fast boot expects > that the memory type is WB.
Yes.
>> >> static u8 mtrr_default_type(struct kvm_mtrr *mtrr_state) >> { >> if (mtrr_is_enabled(mtrr_state)) >> return mtrr_state->deftype & >> IA32_MTRR_DEF_TYPE_TYPE_MASK; >> else >> return MTRR_TYPE_UNCACHABLE; >> } >> >> ? Then it's easy to add a quirk that makes the default WRITEBACK until >> MTRRs are enabled. > > It is the wrong configure in OVMF... shall we need to adjust KVM to satisfy > OVMF?
That's what quirks are for... The firmware should still be fixed of course.
Paolo
| |