Hi Pavel,
Thanks for getting to the bottom of this.
On 1 December 2015 at 14:03, Pavel Fedin <p.fedin@xxxxxxxxxxx> wrote:
> This function takes stage-II physical addresses (A.K.A. IPA), on input, not
> real physical addresses. This causes kvm_is_device_pfn() to return wrong
> values, depending on how much guest and host memory maps match. This
> results in completely broken KVM on some boards. The problem has been
> caught on Samsung proprietary hardware.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: e6fab5442345 ("ARM/arm64: KVM: test properly for a PTE's uncachedness")
>
That commit is not in a release yet, so no need for cc stable
> Signed-off-by: Pavel Fedin <p.fedin@xxxxxxxxxxx>
> ---
> arch/arm/kvm/mmu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> 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?
And instead of reverting, could we fix this properly instead?
> kvm_flush_dcache_pte(*pte);
> } while (pte++, addr += PAGE_SIZE, addr != end);
> }
> --
> 2.4.4
>
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