summaryrefslogtreecommitdiff
path: root/arch/powerpc
diff options
context:
space:
mode:
authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2015-03-30 10:39:12 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2015-04-17 11:23:24 +1000
commit5e1d44aef1673b504dde475aa714b1bdb9b875c4 (patch)
tree714b46d9dc7be08812ada52878088dc2e8165b5c /arch/powerpc
parent1cbee462a5afc1cc30389915b3d18bdcb3c47ad6 (diff)
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')
-rw-r--r--arch/powerpc/include/asm/kvm_book3s_64.h5
-rw-r--r--arch/powerpc/kvm/e500_mmu_host.c20
2 files changed, 16 insertions, 9 deletions
diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index 14619a59ec09..23b724c746e9 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -290,7 +290,10 @@ static inline pte_t kvmppc_read_update_linux_pte(pte_t *ptep, int writing,
pte_t old_pte, new_pte = __pte(0);
while (1) {
- old_pte = *ptep;
+ /*
+ * Make sure we don't reload from ptep
+ */
+ old_pte = READ_ONCE(*ptep);
/*
* wait until _PAGE_BUSY is clear then set it atomically
*/
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);