Hi Alex,
On 9/2/20 7:01 PM, Alexandru Elisei wrote:
On 9/2/20 2:23 AM, Gavin Shan wrote:
On 9/1/20 11:33 PM, Alexandru Elisei wrote:
When userspace uses hugetlbfs for the VM memory, user_mem_abort() tries to
use the same block size to map the faulting IPA in stage 2. If stage 2
cannot use the same size mapping because the block size doesn't fit in the
memslot or the memslot is not properly aligned, user_mem_abort() will fall
back to a page mapping, regardless of the block size. We can do better for
PUD backed hugetlbfs by checking if a PMD block mapping is possible before
deciding to use a page.
vma_pagesize is an unsigned long, use 1UL instead of 1ULL when assigning
its value.
Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
---
arch/arm64/kvm/mmu.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 25e7dc52c086..f590f7355cda 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1871,15 +1871,24 @@ static int user_mem_abort(struct kvm_vcpu *vcpu,
phys_addr_t fault_ipa,
else
vma_shift = PAGE_SHIFT;
- vma_pagesize = 1ULL << vma_shift;
if (logging_active ||
- (vma->vm_flags & VM_PFNMAP) ||
- !fault_supports_stage2_huge_mapping(memslot, hva, vma_pagesize)) {
+ (vma->vm_flags & VM_PFNMAP)) {
force_pte = true;
- vma_pagesize = PAGE_SIZE;
vma_shift = PAGE_SHIFT;
}
It looks incorrect because @vma_pagesize wasn't initialized when
it's passed to fault_supports_stage2_huge_mapping() for the checking.
It's assumed you missed the following changes according to the commit
log:
fault_supports_stage2_huge_mapping(memslot, hva, (1UL << vma_shift))
I'm not sure what you mean. Maybe you've misread the diff? Because the above call
to fault_supports_stage2_huge_mapping() was removed by the patch.
Yeah, your guess is correct as I looked into the removed code :)
+ if (vma_shift == PUD_SHIFT &&
+ !fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
+ vma_shift = PMD_SHIFT;
+
+ if (vma_shift == PMD_SHIFT &&
+ !fault_supports_stage2_huge_mapping(memslot, hva, PMD_SIZE)) {
+ force_pte = true;
+ vma_shift = PAGE_SHIFT;
+ }
+
+ vma_pagesize = 1UL << vma_shift;
+> /*
* The stage2 has a minimum of 2 level table (For arm64 see
* kvm_arm_setup_stage2()). Hence, we are guaranteed that we can
@@ -1889,7 +1898,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu,
phys_addr_t fault_ipa,
*/
if (vma_pagesize == PMD_SIZE ||
(vma_pagesize == PUD_SIZE && kvm_stage2_has_pmd(kvm)))
- gfn = (fault_ipa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
+ gfn = (fault_ipa & ~(vma_pagesize - 1)) >> PAGE_SHIFT;
mmap_read_unlock(current->mm);
/* We need minimum second+third level pages */
Thanks,
Gavin
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
