On Tue, Apr 02, 2019 at 12:06:16PM +0100, Suzuki K Poulose wrote:
> With commit a80868f398554842b14, we no longer ensure that the
> THP page is properly aligned in the guest IPA. Skip the stage2
> huge mapping for unaligned IPA backed by transparent hugepages.
>
> Fixes: a80868f398554842b14 ("KVM: arm/arm64: Enforce PTE mappings at stage2 when needed")
> Reported-by: Eric Auger <eric.auger@xxxxxxxxxx>
> Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> Cc: Chirstoffer Dall <christoffer.dall@xxxxxxx>
> Cc: Zenghui Yu <yuzenghui@xxxxxxxxxx>
> Cc: Zheng Xiang <zhengxiang9@xxxxxxxxxx>
> Tested-by: Eric Auger <eric.auger@xxxxxxx>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> ---
> virt/kvm/arm/mmu.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index 27c9583..4a22f5b 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -1412,7 +1412,9 @@ static bool transparent_hugepage_adjust(kvm_pfn_t *pfnp, phys_addr_t *ipap)
> * page accordingly.
> */
> mask = PTRS_PER_PMD - 1;
> - VM_BUG_ON((gfn & mask) != (pfn & mask));
> + /* Skip memslots with unaligned IPA and user address */
> + if ((gfn & mask) != (pfn & mask))
> + return false;
> if (pfn & mask) {
> *ipap &= PMD_MASK;
> kvm_release_pfn_clean(pfn);
> --
> 2.7.4
I was able to reproduce this issue on v5.1-rc3 on a SoftIron Overdrive 1000
(AMD Seattle (Rev.B1)) with defconfig+ARM64_64K_PAGES with:
qemu-system-aarch64 -cpu host -machine type=virt,accel=kvm -nographic -smp 4
-m 4096 -kernel /boot/vmlinuz-4.9.0-7-arm64 --append "console=ttyAMA0
default_hugepagesz=2M hugepages=256"
The 'default_hugepagesz=2M hugepages=256' had no effect on the reproducibility,
however the guest only intermittently failed to boot. Applying the above
patch fixed this and the guest boots every time.
Tested-by: Andrew Murray <andrew.murray@xxxxxxx>
Thanks,
Andrew Murray
>
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