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KVM: arm64: Assume non-PFNMAP/MIXEDMAP VMAs can be mapped cacheable

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Despite its name, kvm_is_device_pfn() is actually used to determine if a
given PFN has a kernel mapping that can be used to perform cache
maintenance, as it calls pfn_is_map_memory() internally.

Expand the helper into its single callsite and further condition the
check on the VMA having either VM_PFNMAP or VM_MIXEDMAP set. VMAs that
set neither of these flags must always contain Normal, struct page
backed memory with valid aliases in the kernel address space.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Tested-by: Donald Dutile <ddutile@redhat.com>
Signed-off-by: Ankit Agrawal <ankita@nvidia.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20250705071717.5062-3-ankita@nvidia.com
[ Oliver: fixed typos, refined changelog ]
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Ankit Agrawal
2025-07-05 07:17:13 +00:00
committed by Oliver Upton
parent 8cc9dc1ae4
commit 216887f79d
1 changed files with 4 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/arm64/kvm/mmu.c
+4 -6
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@@ -193,11 +193,6 @@ int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm,
return 0;
}
static bool kvm_is_device_pfn(unsigned long pfn)
{
return !pfn_is_map_memory(pfn);
}
static void *stage2_memcache_zalloc_page(void *arg)
{
struct kvm_mmu_memory_cache *mc = arg;
@@ -1492,6 +1487,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
struct kvm_pgtable *pgt;
struct page *page;
vm_flags_t vm_flags;
enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_HANDLE_FAULT | KVM_PGTABLE_WALK_SHARED;
if (fault_is_perm)
@@ -1619,6 +1615,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
vfio_allow_any_uc = vma->vm_flags & VM_ALLOW_ANY_UNCACHED;
vm_flags = vma->vm_flags;
/* Don't use the VMA after the unlock -- it may have vanished */
vma = NULL;
@@ -1642,7 +1640,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (is_error_noslot_pfn(pfn))
return -EFAULT;
if (kvm_is_device_pfn(pfn)) {
if (vm_flags & (VM_PFNMAP | VM_MIXEDMAP) && !pfn_is_map_memory(pfn)) {
/*
* If the page was identified as device early by looking at
* the VMA flags, vma_pagesize is already representing the