On 3 December 2015 at 08:14, Pavel Fedin <p.fedin@xxxxxxxxxxx> wrote:
> Hello!
>
>> > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
>> > index 7dace90..51ad98f 100644
>> > --- a/arch/arm/kvm/mmu.c
>> > +++ b/arch/arm/kvm/mmu.c
>> > @@ -310,7 +310,8 @@ static void stage2_flush_ptes(struct kvm *kvm, pmd_t *pmd,
>> >
>> > pte = pte_offset_kernel(pmd, addr);
>> > do {
>> > - if (!pte_none(*pte) && !kvm_is_device_pfn(__phys_to_pfn(addr)))
>> > + if (!pte_none(*pte) &&
>> > + (pte_val(*pte) & PAGE_S2_DEVICE) != PAGE_S2_DEVICE)
>>
>> I think your analysis is correct, but does that not apply to both instances?
>
> No no, another one is correct, since it operates on real PFN (at least looks like so). I have verified my fix against the original problem (crash on Exynos5410 without generic timer), and it still works fine there.
>
I don't think so. Regardless of whether you are manipulating HYP
mappings or stage-2 mappings, the physical address is always the
output, not the input of the translation, so addr is always either a
virtual address or a intermediate physical address, whereas
pfn_valid() operates on host physical addresses.
>> And instead of reverting, could we fix this properly instead?
>
> Of course, i'm not against alternate approaches, feel free to. I've just suggested what i could, to fix things quickly. I'm indeed no expert in KVM memory management yet. After all, this is what mailing lists are for.
>
OK. I will follow up with a patch, as Christoffer requested. I'd
appreciate it if you could test to see if it also fixes the current
issue, and the original arch timer issue.
Thanks,
Ard.
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