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| author |   Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2015-03-30 10:39:12 +0530 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2015-04-17 11:23:24 +1000 |
| commit | 5e1d44aef1673b504dde475aa714b1bdb9b875c4 (patch) | |
| tree | 714b46d9dc7be08812ada52878088dc2e8165b5c /arch/powerpc/kvm | |
| parent | Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux into fixes (diff) | |
| download | linux-dev-5e1d44aef1673b504dde475aa714b1bdb9b875c4.tar.xz linux-dev-5e1d44aef1673b504dde475aa714b1bdb9b875c4.zip | |
KVM: PPC: Use READ_ONCE when dereferencing pte_t pointer
pte can get updated from other CPUs as part of multiple activities
like THP split, huge page collapse, unmap. We need to make sure we
don't reload the pte value again and again for different checks.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kvm')
| -rw-r--r-- | arch/powerpc/kvm/e500_mmu_host.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c index cc536d4a75ef..5840d546aa03 100644 --- a/arch/powerpc/kvm/e500_mmu_host.c +++ b/arch/powerpc/kvm/e500_mmu_host.c @@ -469,14 +469,18 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, pgdir = vcpu_e500->vcpu.arch.pgdir; ptep = lookup_linux_ptep(pgdir, hva, &tsize_pages); - if (pte_present(*ptep)) - wimg = (*ptep >> PTE_WIMGE_SHIFT) & MAS2_WIMGE_MASK; - else { - if (printk_ratelimit()) - pr_err("%s: pte not present: gfn %lx, pfn %lx\n", - __func__, (long)gfn, pfn); - ret = -EINVAL; - goto out; + if (ptep) { + pte_t pte = READ_ONCE(*ptep); + + if (pte_present(pte)) + wimg = (pte_val(pte) >> PTE_WIMGE_SHIFT) & + MAS2_WIMGE_MASK; + else { + pr_err_ratelimited("%s: pte not present: gfn %lx,pfn %lx\n", + __func__, (long)gfn, pfn); + ret = -EINVAL; + goto out; + } } kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg); |