Hi Marc,

Noticed this patch while catching up with the lists.

Marc Zyngier maz@kernel.org writes:

For the obscure cases where PMD and PUD are the same size (64kB pages with 42bit VA, for example, which results in only two levels of page tables), we can't map anything as a PUD, because there is... erm... no PUD to speak of. Everything is either a PMD or a PTE.

So let's only try and map a PUD when its size is different from that of a PMD.

Cc: stable@vger.kernel.org Fixes: b8e0ba7c8bea ("KVM: arm64: Add support for creating PUD hugepages at stage 2") Reported-by: Gavin Shan gshan@redhat.com Reported-by: Eric Auger eric.auger@redhat.com Reviewed-by: Alexandru Elisei alexandru.elisei@arm.com Reviewed-by: Gavin Shan gshan@redhat.com Tested-by: Gavin Shan gshan@redhat.com Tested-by: Eric Auger eric.auger@redhat.com Tested-by: Alexandru Elisei alexandru.elisei@arm.com Signed-off-by: Marc Zyngier maz@kernel.org

---

arch/arm64/kvm/mmu.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 0121ef2c7c8d..16b8660ddbcc 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1964,7 +1964,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, (fault_status == FSC_PERM && stage2_is_exec(mmu, fault_ipa, vma_pagesize));

• if (vma_pagesize == PUD_SIZE) {

• /*

• * If PUD_SIZE == PMD_SIZE, there is no real PUD level, and
  

• * all we have is a 2-level page table. Trying to map a PUD in
  

• * this case would be fatally wrong.
  

• */
  

• if (PUD_SIZE != PMD_SIZE && vma_pagesize == PUD_SIZE) { pud_t new_pud = kvm_pfn_pud(pfn, mem_type);

new_pud = kvm_pud_mkhuge(new_pud);

Good catch! Missed the 64kb / 42b VA case while adding the initial support.

Thanks for fixing it.

Punit