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KVM: arm64: Avoid mapping size adjustment on permission fault

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Since we only support PMD-sized mappings for THP, getting
a permission fault on a level that results in a mapping
being larger than PAGE_SIZE is a sure indication that we have
already upgraded our mapping to a PMD.

In this case, there is no need to try and parse userspace page
tables, as the fault information already tells us everything.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210726153552.1535838-4-maz@kernel.org
This commit is contained in:
Marc Zyngier 2021-07-26 16:35:49 +01:00
parent 6011cf68c8
commit f2cc327303
1 changed files with 8 additions and 3 deletions
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11
arch/arm64/kvm/mmu.c
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@ -1076,9 +1076,14 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
* If we are not forced to use page mapping, check if we are
* backed by a THP and thus use block mapping if possible.
*/
if (vma_pagesize == PAGE_SIZE && !(force_pte || device))
vma_pagesize = transparent_hugepage_adjust(kvm, memslot, hva,
&pfn, &fault_ipa);
if (vma_pagesize == PAGE_SIZE && !(force_pte || device)) {
if (fault_status == FSC_PERM && fault_granule > PAGE_SIZE)
vma_pagesize = fault_granule;
else
vma_pagesize = transparent_hugepage_adjust(kvm, memslot,
hva, &pfn,
&fault_ipa);
}
if (fault_status != FSC_PERM && !device && kvm_has_mte(kvm)) {
/* Check the VMM hasn't introduced a new VM_SHARED VMA */