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powerpc/kvm/book3s: use find_kvm_host_pte in pute_tce functions 

Current code just hold rmap lock to ensure parallel page table update is
prevented. That is not sufficient. The kernel should also check whether
a mmu_notifer callback was running in parallel.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-16-aneesh.kumar@linux.ibm.com
This commit is contained in:
Aneesh Kumar K.V 2020-05-05 12:47:22 +05:30 committed by Michael Ellerman
parent e3d8ed5518
commit 7769a3394b
1 changed files with 24 additions and 6 deletions
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30
arch/powerpc/kvm/book3s_64_vio_hv.c
View File

@ -437,8 +437,8 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
return H_SUCCESS;
}
static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu,
unsigned long ua, unsigned long *phpa)
static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu, unsigned long mmu_seq,
unsigned long ua, unsigned long *phpa)
{
pte_t *ptep, pte;
unsigned shift = 0;
@ -452,10 +452,17 @@ static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu,
* to exit which will agains result in the below page table walk
* to finish.
*/
ptep = __find_linux_pte(vcpu->arch.pgdir, ua, NULL, &shift);
if (!ptep || !pte_present(*ptep))
/* an rmap lock won't make it safe. because that just ensure hash
* page table entries are removed with rmap lock held. After that
* mmu notifier returns and we go ahead and removing ptes from Qemu page table.
*/
ptep = find_kvm_host_pte(vcpu->kvm, mmu_seq, ua, &shift);
if (!ptep)
return -ENXIO;
pte = READ_ONCE(*ptep);
if (!pte_present(pte))
return -ENXIO;
pte = *ptep;
if (!shift)
shift = PAGE_SHIFT;
@ -477,10 +484,12 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
unsigned long liobn, unsigned long ioba,
unsigned long tce_list, unsigned long npages)
{
struct kvm *kvm = vcpu->kvm;
struct kvmppc_spapr_tce_table *stt;
long i, ret = H_SUCCESS;
unsigned long tces, entry, ua = 0;
unsigned long *rmap = NULL;
unsigned long mmu_seq;
bool prereg = false;
struct kvmppc_spapr_tce_iommu_table *stit;
@ -488,6 +497,12 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
if (kvm_is_radix(vcpu->kvm))
return H_TOO_HARD;
/*
* used to check for invalidations in progress
*/
mmu_seq = kvm->mmu_notifier_seq;
smp_rmb();
stt = kvmppc_find_table(vcpu->kvm, liobn);
if (!stt)
return H_TOO_HARD;
@ -547,7 +562,9 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
* real page.
*/
lock_rmap(rmap);
if (kvmppc_rm_ua_to_hpa(vcpu, ua, &tces)) {
arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock);
if (kvmppc_rm_ua_to_hpa(vcpu, mmu_seq, ua, &tces)) {
ret = H_TOO_HARD;
goto unlock_exit;
}
@ -593,6 +610,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
if (rmap)
unlock_rmap(rmap);
arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock);
return ret;
}