github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-27 11:02:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

KVM: arm64: Skip cache maintenance for non-cacheable pKVM mappings

Browse Source 
The pKVM flush path walks its own pkvm_mappings list and cleans the
data cache for every mapping, unlike the generic stage-2 walker it
shadows, which skips non-cacheable leaves. Cleaning the cacheable
alias of a non-cacheable mapping is pointless and can corrupt a
device endpoint. Record whether a mapping is non-cacheable in spare
bits of nr_pages and skip cache maintenance for it.

Fixes: e912efed48 ("KVM: arm64: Introduce the EL1 pKVM MMU")
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Bradley Morgan <include@grrlz.net>
[tabba: use Marc's anonymous bitfield in place of the open-coded mask and helpers]
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Tested-by: Bradley Morgan <include@grrlz.net> # On pixel 7, Android 17 CP2A.260705.006
Test: Bradley Morgan <include@grrlz.net> # On QEMU arm64 host
Link: https://patch.msgid.link/20260717130317.1953574-2-fuad.tabba@linux.dev
Signed-off-by: Oliver Upton <oupton@kernel.org>
This commit is contained in:
Bradley Morgan 2026-07-17 14:03:11 +01:00 committed by Oliver Upton
parent 734dc8c01c
commit fff4eb33ff
2 changed files with 13 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/arm64/include/asm/kvm_pkvm.h
View File

@ -195,7 +195,10 @@ struct pkvm_mapping {
struct rb_node node;
u64 gfn;
u64 pfn;
u64 nr_pages;
struct {
u64 nr_pages:48;
u64 nc:1;
};
u64 __subtree_last; /* Internal member for interval tree */
};

15
arch/arm64/kvm/pkvm.c
View File

@ -366,7 +366,7 @@ static int __pkvm_pgtable_stage2_unshare(struct kvm_pgtable *pgt, u64 start, u64
for_each_mapping_in_range_safe(pgt, start, end, mapping) {
ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_guest, handle, mapping->gfn,
mapping->nr_pages);
(u64)mapping->nr_pages);
if (WARN_ON(ret))
return ret;
pkvm_mapping_remove(mapping, &pgt->pkvm_mappings);
@ -470,6 +470,7 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
mapping->gfn = gfn;
mapping->pfn = pfn;
mapping->nr_pages = size / PAGE_SIZE;
mapping->nc = !!(prot & (KVM_PGTABLE_PROT_DEVICE | KVM_PGTABLE_PROT_NORMAL_NC));
pkvm_mapping_insert(mapping, &pgt->pkvm_mappings);
return ret;
@ -500,7 +501,7 @@ int pkvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
lockdep_assert_held(&kvm->mmu_lock);
for_each_mapping_in_range_safe(pgt, addr, addr + size, mapping) {
ret = kvm_call_hyp_nvhe(__pkvm_host_wrprotect_guest, handle, mapping->gfn,
mapping->nr_pages);
(u64)mapping->nr_pages);
if (WARN_ON(ret))
break;
}
@ -514,9 +515,11 @@ int pkvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
struct pkvm_mapping *mapping;
lockdep_assert_held(&kvm->mmu_lock);
for_each_mapping_in_range_safe(pgt, addr, addr + size, mapping)
__clean_dcache_guest_page(pfn_to_kaddr(mapping->pfn),
PAGE_SIZE * mapping->nr_pages);
for_each_mapping_in_range_safe(pgt, addr, addr + size, mapping) {
if (!mapping->nc)
__clean_dcache_guest_page(pfn_to_kaddr(mapping->pfn),
PAGE_SIZE * mapping->nr_pages);
}
return 0;
}
@ -534,7 +537,7 @@ bool pkvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr, u64
lockdep_assert_held(&kvm->mmu_lock);
for_each_mapping_in_range_safe(pgt, addr, addr + size, mapping)
young |= kvm_call_hyp_nvhe(__pkvm_host_test_clear_young_guest, handle, mapping->gfn,
mapping->nr_pages, mkold);
(u64)mapping->nr_pages, mkold);
return young;
}