KVM: arm64: Try PMD block mappings if PUD mappings are not supported (523b3999) · Commits · 戴 / test

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 the same block 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 supported 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@arm.com> Signed-off-by:

Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20200910133351.118191-1-alexandru.elisei@arm.com

arch/arm64/kvm/mmu.c

+14 −5

Original line number	Diff line number	Diff line
		@@ -779,16 +779,25 @@ 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;
		}

		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;
		if (vma_pagesize == PMD_SIZE \|\| vma_pagesize == PUD_SIZE)
		fault_ipa &= huge_page_mask(hstate_vma(vma));
		fault_ipa &= ~(vma_pagesize - 1);

		gfn = fault_ipa >> PAGE_SHIFT;
		mmap_read_unlock(current->mm);

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