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Thu, 06 Feb 2020 03:12:34 +0000 Received: from b03ledav005.gho.boulder.ibm.com (b03ledav005.gho.boulder.ibm.com [9.17.130.236]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 0163CXS547448330 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 6 Feb 2020 03:12:33 GMT Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E98A2BE04F; Thu, 6 Feb 2020 03:12:32 +0000 (GMT) Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2FD1ABE051; Thu, 6 Feb 2020 03:12:23 +0000 (GMT) Received: from LeoBras.aus.stglabs.ibm.com (unknown [9.85.163.250]) by b03ledav005.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 6 Feb 2020 03:12:22 +0000 (GMT) From: Leonardo Bras To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Arnd Bergmann , Andrew Morton , "Aneesh Kumar K.V" , Nicholas Piggin , Christophe Leroy , Steven Price , Robin Murphy , Leonardo Bras , Mahesh Salgaonkar , Balbir Singh , Reza Arbab , Thomas Gleixner , Allison Randal , Greg Kroah-Hartman , Mike Rapoport , Michal Suchanek Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v6 09/11] powerpc/kvm/book3s_64: Use functions to track lockless pgtbl walks Date: Thu, 6 Feb 2020 00:08:58 -0300 Message-Id: <20200206030900.147032-10-leonardo@linux.ibm.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200206030900.147032-1-leonardo@linux.ibm.com> References: <20200206030900.147032-1-leonardo@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-02-05_06:2020-02-04,2020-02-05 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 malwarescore=0 suspectscore=0 phishscore=0 clxscore=1015 adultscore=0 mlxlogscore=588 bulkscore=0 spamscore=0 lowpriorityscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002060022 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Applies the new tracking functions to all book3s_64 related functions that do lockless pagetable walks. Adds comments explaining that some lockless pagetable walks don't need protection due to guest pgd not being a target of THP collapse/split, or due to being called from Realmode + MSR_EE = 0. Given that some of these functions always are called in realmode, we use __{begin,end}_lockless_pgtbl_walk so we can decide when to disable interrupts. local_irq_{save,restore} is already inside {begin,end}_lockless_pgtbl_walk, so there is no need to repeat it here. Variable that saves the irq mask was renamed from flags to irq_mask so it doesn't lose meaning now it's not directly passed to local_irq_* functions. There are also a function that uses local_irq_{en,dis}able, so the return value of begin_lockless_pgtbl_walk() is ignored and we pass IRQS_ENABLED to end_lockless_pgtbl_walk() to mimic the effect of local_irq_enable(). Signed-off-by: Leonardo Bras --- arch/powerpc/kvm/book3s_64_mmu_hv.c | 6 ++--- arch/powerpc/kvm/book3s_64_mmu_radix.c | 34 +++++++++++++++++++++++--- arch/powerpc/kvm/book3s_64_vio_hv.c | 6 ++++- 3 files changed, 39 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 6c372f5c61b6..e7ce29a5df60 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -605,19 +605,19 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, /* if the guest wants write access, see if that is OK */ if (!writing && hpte_is_writable(r)) { pte_t *ptep, pte; - unsigned long flags; + unsigned long irq_mask; /* * We need to protect against page table destruction * hugepage split and collapse. */ - local_irq_save(flags); + irq_mask = begin_lockless_pgtbl_walk(); ptep = find_current_mm_pte(mm->pgd, hva, NULL, NULL); if (ptep) { pte = kvmppc_read_update_linux_pte(ptep, 1); if (__pte_write(pte)) write_ok = 1; } - local_irq_restore(flags); + end_lockless_pgtbl_walk(irq_mask); } } diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c index 803940d79b73..cda2e455baf2 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -813,20 +813,20 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu, * Read the PTE from the process' radix tree and use that * so we get the shift and attribute bits. */ - local_irq_disable(); + begin_lockless_pgtbl_walk(); ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift); /* * If the PTE disappeared temporarily due to a THP * collapse, just return and let the guest try again. */ if (!ptep) { - local_irq_enable(); + end_lockless_pgtbl_walk(IRQS_ENABLED); if (page) put_page(page); return RESUME_GUEST; } pte = *ptep; - local_irq_enable(); + end_lockless_pgtbl_walk(IRQS_ENABLED); /* If we're logging dirty pages, always map single pages */ large_enable = !(memslot->flags & KVM_MEM_LOG_DIRTY_PAGES); @@ -980,10 +980,16 @@ int kvm_unmap_radix(struct kvm *kvm, struct kvm_memory_slot *memslot, return 0; } + /* + * We are walking the secondary (partition-scoped) page table here. + * We can do this without disabling irq because the Linux MM + * subsystem doesn't do THP splits and collapses on this tree. + */ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (ptep && pte_present(*ptep)) kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot, kvm->arch.lpid); + return 0; } @@ -1000,6 +1006,11 @@ int kvm_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot, if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE) return ref; + /* + * We are walking the secondary (partition-scoped) page table here. + * We can do this without disabling irq because the Linux MM + * subsystem doesn't do THP splits and collapses on this tree. + */ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (ptep && pte_present(*ptep) && pte_young(*ptep)) { old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_ACCESSED, 0, @@ -1027,6 +1038,11 @@ int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot, if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE) return ref; + /* + * We are walking the secondary (partition-scoped) page table here. + * We can do this without disabling irq because the Linux MM + * subsystem doesn't do THP splits and collapses on this tree. + */ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (ptep && pte_present(*ptep) && pte_young(*ptep)) ref = 1; @@ -1047,6 +1063,11 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm, if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE) return ret; + /* + * We are walking the secondary (partition-scoped) page table here. + * We can do this without disabling irq because the Linux MM + * subsystem doesn't do THP splits and collapses on this tree. + */ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) { ret = 1; @@ -1063,6 +1084,7 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm, 1UL << shift); spin_unlock(&kvm->mmu_lock); } + return ret; } @@ -1108,6 +1130,12 @@ void kvmppc_radix_flush_memslot(struct kvm *kvm, gpa = memslot->base_gfn << PAGE_SHIFT; spin_lock(&kvm->mmu_lock); for (n = memslot->npages; n; --n) { + /* + * We are walking the secondary (partition-scoped) page table + * here. + * We can do this without disabling irq because the Linux MM + * subsystem doesn't do THP splits and collapses on this tree. + */ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (ptep && pte_present(*ptep)) kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot, diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index ab6eeb8e753e..83c70c1557e4 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -453,10 +453,14 @@ 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. */ + __begin_lockless_pgtbl_walk(false); ptep = __find_linux_pte(vcpu->arch.pgdir, ua, NULL, &shift); - if (!ptep || !pte_present(*ptep)) + if (!ptep || !pte_present(*ptep)) { + __end_lockless_pgtbl_walk(0, false); return -ENXIO; + } pte = *ptep; + __end_lockless_pgtbl_walk(0, false); if (!shift) shift = PAGE_SHIFT;