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Thu, 03 Oct 2019 01:35:37 +0000 Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x931Zare60686794 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 3 Oct 2019 01:35:36 GMT Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4C9BF78063; Thu, 3 Oct 2019 01:35:36 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D898F7805C; Thu, 3 Oct 2019 01:35:23 +0000 (GMT) Received: from LeoBras.ibmuc.com (unknown [9.85.174.224]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 3 Oct 2019 01:35:23 +0000 (GMT) From: Leonardo Bras To: 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 v5 08/11] powerpc/kvm/book3s_hv: Applies counting method to monitor lockless pgtbl walks Date: Wed, 2 Oct 2019 22:33:22 -0300 Message-Id: <20191003013325.2614-9-leonardo@linux.ibm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191003013325.2614-1-leonardo@linux.ibm.com> References: <20191003013325.2614-1-leonardo@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-10-03_01:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=997 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910030012 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Song Liu , Michal Hocko , "Peter Zijlstra \(Intel\)" , "Dmitry V. Levin" , Keith Busch , Paul Mackerras , Christoph Lameter , Ira Weiny , Thomas Gleixner , Elena Reshetova , Andrea Arcangeli , Santosh Sivaraj , Davidlohr Bueso , "Aneesh Kumar K.V" , Bartlomiej Zolnierkiewicz , Mike Rapoport , Jason Gunthorpe , Allison Randal , Mahesh Salgaonkar , Leonardo Bras , Alexey Dobriyan , Ingo Molnar , Ralph Campbell , Arnd Bergmann , Jann Horn , John Hubbard , Jesper Dangaard Brouer , Nicholas Piggin , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Mathieu Desnoyers , Al Viro , Andrey Ryabinin , Dan Williams , Reza Arbab , Vlastimil Babka , Christian Brauner , Greg Kroah-Hartman , Souptick Joarder , Andrew Morton , Logan Gunthorpe , Roman Gushchin , "Kirill A. Shutemov" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Applies the counting-based method for monitoring all book3s_hv 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 kvmppc_do_h_enter: Fixes where local_irq_restore() must be placed (after the last usage of ptep). Given that some of these functions can be called in real mode, and others always are, we use __{begin,end}_lockless_pgtbl_walk so we can decide when to disable interrupts. Signed-off-by: Leonardo Bras --- arch/powerpc/kvm/book3s_hv_nested.c | 22 ++++++++++++++++++-- arch/powerpc/kvm/book3s_hv_rm_mmu.c | 32 ++++++++++++++++------------- 2 files changed, 38 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c index cdf30c6eaf54..89944c699fd6 100644 --- a/arch/powerpc/kvm/book3s_hv_nested.c +++ b/arch/powerpc/kvm/book3s_hv_nested.c @@ -803,7 +803,11 @@ static void kvmhv_update_nest_rmap_rc(struct kvm *kvm, u64 n_rmap, if (!gp) return; - /* Find the pte */ + /* Find the pte: + * We are walking the nested guest (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(gp->shadow_pgtable, gpa, NULL, &shift); /* * If the pte is present and the pfn is still the same, update the pte. @@ -853,7 +857,11 @@ static void kvmhv_remove_nest_rmap(struct kvm *kvm, u64 n_rmap, if (!gp) return; - /* Find and invalidate the pte */ + /* Find and invalidate the pte: + * We are walking the nested guest (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(gp->shadow_pgtable, gpa, NULL, &shift); /* Don't spuriously invalidate ptes if the pfn has changed */ if (ptep && pte_present(*ptep) && ((pte_val(*ptep) & mask) == hpa)) @@ -921,6 +929,11 @@ static bool kvmhv_invalidate_shadow_pte(struct kvm_vcpu *vcpu, int shift; spin_lock(&kvm->mmu_lock); + /* + * We are walking the nested guest (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(gp->shadow_pgtable, gpa, NULL, &shift); if (!shift) shift = PAGE_SHIFT; @@ -1362,6 +1375,11 @@ static long int __kvmhv_nested_page_fault(struct kvm_run *run, /* See if can find translation in our partition scoped tables for L1 */ pte = __pte(0); spin_lock(&kvm->mmu_lock); + /* + * 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. + */ pte_p = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (!shift) shift = PAGE_SHIFT; diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c index 220305454c23..a8be42f5be1e 100644 --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c @@ -210,7 +210,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, pte_t *ptep; unsigned int writing; unsigned long mmu_seq; - unsigned long rcbits, irq_flags = 0; + unsigned long rcbits, irq_mask = 0; if (kvm_is_radix(kvm)) return H_FUNCTION; @@ -252,12 +252,8 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, * If we had a page table table change after lookup, we would * retry via mmu_notifier_retry. */ - if (!realmode) - local_irq_save(irq_flags); - /* - * If called in real mode we have MSR_EE = 0. Otherwise - * we disable irq above. - */ + irq_mask = __begin_lockless_pgtbl_walk(kvm->mm, !realmode); + ptep = __find_linux_pte(pgdir, hva, NULL, &hpage_shift); if (ptep) { pte_t pte; @@ -272,8 +268,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, * to <= host page size, if host is using hugepage */ if (host_pte_size < psize) { - if (!realmode) - local_irq_restore(flags); + __end_lockless_pgtbl_walk(kvm->mm, irq_mask, !realmode); return H_PARAMETER; } pte = kvmppc_read_update_linux_pte(ptep, writing); @@ -287,8 +282,6 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, pa |= gpa & ~PAGE_MASK; } } - if (!realmode) - local_irq_restore(irq_flags); ptel &= HPTE_R_KEY | HPTE_R_PP0 | (psize-1); ptel |= pa; @@ -302,8 +295,10 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, /*If we had host pte mapping then Check WIMG */ if (ptep && !hpte_cache_flags_ok(ptel, is_ci)) { - if (is_ci) + if (is_ci) { + __end_lockless_pgtbl_walk(kvm->mm, irq_mask, !realmode); return H_PARAMETER; + } /* * Allow guest to map emulated device memory as * uncacheable, but actually make it cacheable. @@ -311,6 +306,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, ptel &= ~(HPTE_R_W|HPTE_R_I|HPTE_R_G); ptel |= HPTE_R_M; } + __end_lockless_pgtbl_walk(kvm->mm, irq_mask, !realmode); /* Find and lock the HPTEG slot to use */ do_insert: @@ -907,11 +903,19 @@ static int kvmppc_get_hpa(struct kvm_vcpu *vcpu, unsigned long gpa, /* Translate to host virtual address */ hva = __gfn_to_hva_memslot(memslot, gfn); - /* Try to find the host pte for that virtual address */ + /* Try to find the host pte for that virtual address : + * Called by hcall_real_table (real mode + MSR_EE=0) + * Interrupts are disabled here. + */ + __begin_lockless_pgtbl_walk(kvm->mm, false); ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift); - if (!ptep) + if (!ptep) { + __end_lockless_pgtbl_walk(kvm->mm, 0, false); return H_TOO_HARD; + } pte = kvmppc_read_update_linux_pte(ptep, writing); + __end_lockless_pgtbl_walk(kvm->mm, 0, false); + if (!pte_present(pte)) return H_TOO_HARD; -- 2.20.1