From patchwork Fri Mar 17 05:09:57 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Kardashevskiy X-Patchwork-Id: 740162 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3vktwk6qfGz9ryZ for ; Fri, 17 Mar 2017 16:21:10 +1100 (AEDT) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3vktwk5qYCzDr79 for ; Fri, 17 Mar 2017 16:21:10 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from ozlabs.ru (ozlabs.ru [107.173.13.209]) by lists.ozlabs.org (Postfix) with ESMTP id 3vkthC15LlzDqcJ for ; Fri, 17 Mar 2017 16:10:19 +1100 (AEDT) Received: from vpl2.ozlabs.ibm.com (localhost [IPv6:::1]) by ozlabs.ru (Postfix) with ESMTP id AC4BD3A603C2; Fri, 17 Mar 2017 01:10:17 -0400 (EDT) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH kernel v10 08/10] KVM: PPC: Use preregistered memory API to access TCE list Date: Fri, 17 Mar 2017 16:09:57 +1100 Message-Id: <20170317050959.37312-9-aik@ozlabs.ru> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170317050959.37312-1-aik@ozlabs.ru> References: <20170317050959.37312-1-aik@ozlabs.ru> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, Alexey Kardashevskiy , kvm-ppc@vger.kernel.org, Alex Williamson , Paul Mackerras , David Gibson Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" VFIO on sPAPR already implements guest memory pre-registration when the entire guest RAM gets pinned. This can be used to translate the physical address of a guest page containing the TCE list from H_PUT_TCE_INDIRECT. This makes use of the pre-registrered memory API to access TCE list pages in order to avoid unnecessary locking on the KVM memory reverse map as we know that all of guest memory is pinned and we have a flat array mapping GPA to HPA which makes it simpler and quicker to index into that array (even with looking up the kernel page tables in vmalloc_to_phys) than it is to find the memslot, lock the rmap entry, look up the user page tables, and unlock the rmap entry. Note that the rmap pointer is initialized to NULL where declared (not in this patch). If a requested chunk of memory has not been preregistered, this will fall back to non-preregistered case and lock rmap. Signed-off-by: Alexey Kardashevskiy Reviewed-by: David Gibson --- Changes: v4: * removed oneline inlines * now falls back to locking rmap if TCE list is not in preregistered memory v2: * updated the commit log with David's comment --- arch/powerpc/kvm/book3s_64_vio_hv.c | 58 +++++++++++++++++++++++++++---------- 1 file changed, 42 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index 918af76ab2b6..0f145fc7a3a5 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -239,6 +239,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, long i, ret = H_SUCCESS; unsigned long tces, entry, ua = 0; unsigned long *rmap = NULL; + bool prereg = false; stt = kvmppc_find_table(vcpu->kvm, liobn); if (!stt) @@ -259,23 +260,47 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, if (ret != H_SUCCESS) return ret; - if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, &rmap)) - return H_TOO_HARD; + if (mm_iommu_preregistered(vcpu->kvm->mm)) { + /* + * We get here if guest memory was pre-registered which + * is normally VFIO case and gpa->hpa translation does not + * depend on hpt. + */ + struct mm_iommu_table_group_mem_t *mem; - rmap = (void *) vmalloc_to_phys(rmap); + if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, NULL)) + return H_TOO_HARD; - /* - * Synchronize with the MMU notifier callbacks in - * book3s_64_mmu_hv.c (kvm_unmap_hva_hv etc.). - * While we have the rmap lock, code running on other CPUs - * cannot finish unmapping the host real page that backs - * this guest real page, so we are OK to access the host - * real page. - */ - lock_rmap(rmap); - if (kvmppc_rm_ua_to_hpa(vcpu, ua, &tces)) { - ret = H_TOO_HARD; - goto unlock_exit; + mem = mm_iommu_lookup_rm(vcpu->kvm->mm, ua, IOMMU_PAGE_SIZE_4K); + if (mem) + prereg = mm_iommu_ua_to_hpa_rm(mem, ua, &tces) == 0; + } + + if (!prereg) { + /* + * This is usually a case of a guest with emulated devices only + * when TCE list is not in preregistered memory. + * We do not require memory to be preregistered in this case + * so lock rmap and do __find_linux_pte_or_hugepte(). + */ + if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, &rmap)) + return H_TOO_HARD; + + rmap = (void *) vmalloc_to_phys(rmap); + + /* + * Synchronize with the MMU notifier callbacks in + * book3s_64_mmu_hv.c (kvm_unmap_hva_hv etc.). + * While we have the rmap lock, code running on other CPUs + * cannot finish unmapping the host real page that backs + * this guest real page, so we are OK to access the host + * real page. + */ + lock_rmap(rmap); + if (kvmppc_rm_ua_to_hpa(vcpu, ua, &tces)) { + ret = H_TOO_HARD; + goto unlock_exit; + } } for (i = 0; i < npages; ++i) { @@ -289,7 +314,8 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, } unlock_exit: - unlock_rmap(rmap); + if (rmap) + unlock_rmap(rmap); return ret; }