Commit 832cd8eb authored Jul 09, 2024 by Bibo Mao Committed by Xianglai Li Dec 04, 2024

LoongArch: KVM: Add memory barrier before update pmd entry

mainline inclusion
from mainline-v6.11-rc1
commit 32d4b999dadee0a84ac7fe709cae21d29364e1d1
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/IAZJDO


CVE: NA

--------------------------------

When updating pmd entry such as allocating new pmd page or splitting
huge page into normal page, it is necessary to firstly update all pte
entries, and then update pmd entry.

It is weak order with LoongArch system, there will be problem if other
VCPUs see pmd update firstly while ptes are not updated. Here smp_wmb()
is added to assure this.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Xianglai Li <lixianglai@loongson.cn>

parent 5abe310b

arch/loongarch/kvm/mmu.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -163,6 +163,7 @@ static kvm_pte_t kvm_populate_gpa(struct kvm kvm,

		child = kvm_mmu_memory_cache_alloc(cache);
		_kvm_pte_init(child, ctx.invalid_ptes[ctx.level - 1]);
		smp_wmb(); /* Make pte visible before pmd */
		kvm_set_pte(entry, __pa(child));
		} else if (kvm_pte_huge(*entry)) {
		return entry;
		@@ -778,6 +779,7 @@ static kvm_pte_t kvm_split_huge(struct kvm_vcpu vcpu, kvm_pte_t *ptep, gfn_t g
		val += PAGE_SIZE;
		}

		smp_wmb(); /* Make pte visible before pmd */
		/* The later kvm_flush_tlb_gpa() will flush hugepage tlb */
		kvm_set_pte(ptep, __pa(child));