From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kvm-ppc@vger.kernel.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
npiggin@gmail.com, kirill@shutemov.name, leonardo@linux.ibm.com
Subject: [PATCH v2 15/22] powerpc/kvm/book3s: use find_kvm_host_pte in pute_tce functions
Date: Thu, 19 Mar 2020 09:26:02 +0530 [thread overview]
Message-ID: <20200319035609.158654-16-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200319035609.158654-1-aneesh.kumar@linux.ibm.com>
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.
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
arch/powerpc/kvm/book3s_64_vio_hv.c | 30 +++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c
index ab6eeb8e753e..8a6bf12d2e88 100644
--- a/arch/powerpc/kvm/book3s_64_vio_hv.c
+++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
@@ -438,8 +438,8 @@ 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;
@@ -453,10 +453,17 @@ 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;
@@ -478,10 +485,12 @@ 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;
@@ -489,6 +498,12 @@ 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;
@@ -548,7 +563,9 @@ 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;
}
@@ -594,6 +611,7 @@ 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;
}
--
2.24.1
next prev parent reply other threads:[~2020-03-19 4:23 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 3:55 [PATCH v2 00/22] Avoid IPI while updating page table entries Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 01/22] powerpc/pkeys: Avoid using lockless page table walk Aneesh Kumar K.V
2020-04-03 0:28 ` Ram Pai
2020-04-05 13:37 ` Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 02/22] powerpc/pkeys: Check vma before returning key fault error to the user Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 03/22] powerpc/mm/hash64: use _PAGE_PTE when checking for pte_present Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 04/22] powerpc/hash64: Restrict page table lookup using init_mm with __flush_hash_table_range Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 05/22] powerpc/book3s64/hash: Use the pte_t address from the caller Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 06/22] powerpc/mce: Don't reload pte val in addr_to_pfn Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 07/22] powerpc/perf/callchain: Use __get_user_pages_fast in read_user_stack_slow Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 08/22] powerpc/kvm/book3s: switch from raw_spin_*lock to arch_spin_lock Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 09/22] powerpc/kvm/book3s: Add helper to walk partition scoped linux page table Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 10/22] powerpc/kvm/nested: Add helper to walk nested shadow " Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 11/22] powerpc/kvm/book3s: Use kvm helpers to walk shadow or secondary table Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 12/22] powerpc/kvm/book3s: Add helper for host page table walk Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 13/22] powerpc/kvm/book3s: Use find_kvm_host_pte in page fault handler Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 14/22] powerpc/kvm/book3s: Use find_kvm_host_pte in h_enter Aneesh Kumar K.V
2020-03-19 3:56 ` Aneesh Kumar K.V [this message]
2020-03-19 3:56 ` [PATCH v2 16/22] powerpc/kvm/book3s: Avoid using rmap to protect parallel page table update Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 17/22] powerpc/kvm/book3s: use find_kvm_host_pte in kvmppc_book3s_instantiate_page Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 18/22] powerpc/kvm/book3s: Use find_kvm_host_pte in kvmppc_get_hpa Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 19/22] powerpc/kvm/book3s: Use pte_present instead of opencoding _PAGE_PRESENT check Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 20/22] powerpc/mm/book3s64: Avoid sending IPI on clearing PMD Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 21/22] mm: change pmdp_huge_get_and_clear_full take vm_area_struct as arg Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 22/22] powerpc/mm/book3s64: Fix MADV_DONTNEED and parallel page fault race Aneesh Kumar K.V
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