From: Peter Collingbourne <pcc@google.com>
To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu
Cc: kvm@vger.kernel.org, Peter Collingbourne <pcc@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Cornelia Huck <cohuck@redhat.com>,
Steven Price <steven.price@arm.com>,
Marc Zyngier <maz@kernel.org>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will@kernel.org>,
Evgenii Stepanov <eugenis@google.com>
Subject: [PATCH v4 3/8] KVM: arm64: Simplify the sanitise_mte_tags() logic
Date: Tue, 20 Sep 2022 20:51:35 -0700 [thread overview]
Message-ID: <20220921035140.57513-4-pcc@google.com> (raw)
In-Reply-To: <20220921035140.57513-1-pcc@google.com>
From: Catalin Marinas <catalin.marinas@arm.com>
Currently sanitise_mte_tags() checks if it's an online page before
attempting to sanitise the tags. Such detection should be done in the
caller via the VM_MTE_ALLOWED vma flag. Since kvm_set_spte_gfn() does
not have the vma, leave the page unmapped if not already tagged. Tag
initialisation will be done on a subsequent access fault in
user_mem_abort().
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
[pcc@google.com: fix the page initializer]
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Peter Collingbourne <pcc@google.com>
---
arch/arm64/kvm/mmu.c | 40 +++++++++++++++-------------------------
1 file changed, 15 insertions(+), 25 deletions(-)
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 012ed1bc0762..5a131f009cf9 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1056,23 +1056,14 @@ static int get_vma_page_shift(struct vm_area_struct *vma, unsigned long hva)
* - mmap_lock protects between a VM faulting a page in and the VMM performing
* an mprotect() to add VM_MTE
*/
-static int sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn,
- unsigned long size)
+static void sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn,
+ unsigned long size)
{
unsigned long i, nr_pages = size >> PAGE_SHIFT;
- struct page *page;
+ struct page *page = pfn_to_page(pfn);
if (!kvm_has_mte(kvm))
- return 0;
-
- /*
- * pfn_to_online_page() is used to reject ZONE_DEVICE pages
- * that may not support tags.
- */
- page = pfn_to_online_page(pfn);
-
- if (!page)
- return -EFAULT;
+ return;
for (i = 0; i < nr_pages; i++, page++) {
if (!page_mte_tagged(page)) {
@@ -1080,8 +1071,6 @@ static int sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn,
set_page_mte_tagged(page);
}
}
-
- return 0;
}
static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
@@ -1092,7 +1081,6 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
bool write_fault, writable, force_pte = false;
bool exec_fault;
bool device = false;
- bool shared;
unsigned long mmu_seq;
struct kvm *kvm = vcpu->kvm;
struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
@@ -1142,8 +1130,6 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
vma_shift = get_vma_page_shift(vma, hva);
}
- shared = (vma->vm_flags & VM_SHARED);
-
switch (vma_shift) {
#ifndef __PAGETABLE_PMD_FOLDED
case PUD_SHIFT:
@@ -1264,12 +1250,13 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (fault_status != FSC_PERM && !device && kvm_has_mte(kvm)) {
/* Check the VMM hasn't introduced a new VM_SHARED VMA */
- if (!shared)
- ret = sanitise_mte_tags(kvm, pfn, vma_pagesize);
- else
+ if ((vma->vm_flags & VM_MTE_ALLOWED) &&
+ !(vma->vm_flags & VM_SHARED)) {
+ sanitise_mte_tags(kvm, pfn, vma_pagesize);
+ } else {
ret = -EFAULT;
- if (ret)
goto out_unlock;
+ }
}
if (writable)
@@ -1491,15 +1478,18 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
{
kvm_pfn_t pfn = pte_pfn(range->pte);
- int ret;
if (!kvm->arch.mmu.pgt)
return false;
WARN_ON(range->end - range->start != 1);
- ret = sanitise_mte_tags(kvm, pfn, PAGE_SIZE);
- if (ret)
+ /*
+ * If the page isn't tagged, defer to user_mem_abort() for sanitising
+ * the MTE tags. The S2 pte should have been unmapped by
+ * mmu_notifier_invalidate_range_end().
+ */
+ if (kvm_has_mte(kvm) && !page_mte_tagged(pfn_to_page(pfn)))
return false;
/*
--
2.37.3.968.ga6b4b080e4-goog
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next prev parent reply other threads:[~2022-09-21 3:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-21 3:51 [PATCH v4 0/8] KVM: arm64: permit MAP_SHARED mappings with MTE enabled Peter Collingbourne
2022-09-21 3:51 ` [PATCH v4 1/8] mm: Do not enable PG_arch_2 for all 64-bit architectures Peter Collingbourne
2022-09-21 9:17 ` Steven Price
2022-09-21 3:51 ` [PATCH v4 2/8] arm64: mte: Fix/clarify the PG_mte_tagged semantics Peter Collingbourne
2022-09-21 3:51 ` Peter Collingbourne [this message]
2022-09-21 3:51 ` [PATCH v4 4/8] mm: Add PG_arch_3 page flag Peter Collingbourne
2022-09-21 9:17 ` Steven Price
2022-09-21 3:51 ` [PATCH v4 5/8] arm64: mte: Lock a page for MTE tag initialisation Peter Collingbourne
2022-09-21 3:51 ` [PATCH v4 6/8] KVM: arm64: unify the tests for VMAs in memslots when MTE is enabled Peter Collingbourne
2022-09-21 3:51 ` [PATCH v4 7/8] KVM: arm64: permit all VM_MTE_ALLOWED mappings with MTE enabled Peter Collingbourne
2022-09-21 3:51 ` [PATCH v4 8/8] Documentation: document the ABI changes for KVM_CAP_ARM_MTE Peter Collingbourne
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