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Tsirkin" , Jason Wang , Stefan Hajnoczi , Stefano Garzarella , Germano Veit Michel , Raphael Norwitz Subject: [PATCH v1 11/15] libvhost-user: Speedup gpa_to_mem_region() and vu_gpa_to_va() Date: Fri, 2 Feb 2024 22:53:28 +0100 Message-ID: <20240202215332.118728-12-david@redhat.com> In-Reply-To: <20240202215332.118728-1-david@redhat.com> References: <20240202215332.118728-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.276, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1706910918219100005 Content-Type: text/plain; charset="utf-8" Let's speed up GPA to memory region / virtual address lookup. Store the memory regions ordered by guest physical addresses, and use binary search for address translation, as well as when adding/removing memory regions. Most importantly, this will speed up GPA->VA address translation when we have many memslots. Signed-off-by: David Hildenbrand --- subprojects/libvhost-user/libvhost-user.c | 49 +++++++++++++++++++++-- 1 file changed, 45 insertions(+), 4 deletions(-) diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvho= st-user/libvhost-user.c index d036b54ed0..75e47b7bb3 100644 --- a/subprojects/libvhost-user/libvhost-user.c +++ b/subprojects/libvhost-user/libvhost-user.c @@ -199,19 +199,30 @@ vu_panic(VuDev *dev, const char *msg, ...) static VuDevRegion * vu_gpa_to_mem_region(VuDev *dev, uint64_t guest_addr) { - unsigned int i; + int low =3D 0; + int high =3D dev->nregions - 1; =20 /* * Memory regions cannot overlap in guest physical address space. Each * GPA belongs to exactly one memory region, so there can only be one * match. + * + * We store our memory regions ordered by GPA and can simply perform a + * binary search. */ - for (i =3D 0; i < dev->nregions; i++) { - VuDevRegion *cur =3D &dev->regions[i]; + while (low <=3D high) { + unsigned int mid =3D low + (high - low) / 2; + VuDevRegion *cur =3D &dev->regions[mid]; =20 if (guest_addr >=3D cur->gpa && guest_addr < cur->gpa + cur->size)= { return cur; } + if (guest_addr >=3D cur->gpa + cur->size) { + low =3D mid + 1; + } + if (guest_addr < cur->gpa) { + high =3D mid - 1; + } } return NULL; } @@ -273,9 +284,14 @@ vu_remove_all_mem_regs(VuDev *dev) static void _vu_add_mem_reg(VuDev *dev, VhostUserMemoryRegion *msg_region, int fd) { + const uint64_t start_gpa =3D msg_region->guest_phys_addr; + const uint64_t end_gpa =3D start_gpa + msg_region->memory_size; int prot =3D PROT_READ | PROT_WRITE; VuDevRegion *r; void *mmap_addr; + int low =3D 0; + int high =3D dev->nregions - 1; + unsigned int idx; =20 DPRINT("Adding region %d\n", dev->nregions); DPRINT(" guest_phys_addr: 0x%016"PRIx64"\n", @@ -295,6 +311,29 @@ _vu_add_mem_reg(VuDev *dev, VhostUserMemoryRegion *msg= _region, int fd) prot =3D PROT_NONE; } =20 + /* + * We will add memory regions into the array sorted by GPA. Perform a + * binary search to locate the insertion point: it will be at the low + * index. + */ + while (low <=3D high) { + unsigned int mid =3D low + (high - low) / 2; + VuDevRegion *cur =3D &dev->regions[mid]; + + /* Overlap of GPA addresses. */ + if (start_gpa < cur->gpa + cur->size && cur->gpa < end_gpa) { + vu_panic(dev, "regions with overlapping guest physical address= es"); + return; + } + if (start_gpa >=3D cur->gpa + cur->size) { + low =3D mid + 1; + } + if (start_gpa < cur->gpa) { + high =3D mid - 1; + } + } + idx =3D low; + /* * We don't use offset argument of mmap() since the mapped address has * to be page aligned, and we use huge pages. @@ -308,7 +347,9 @@ _vu_add_mem_reg(VuDev *dev, VhostUserMemoryRegion *msg_= region, int fd) DPRINT(" mmap_addr: 0x%016"PRIx64"\n", (uint64_t)(uintptr_t)mmap_addr); =20 - r =3D &dev->regions[dev->nregions]; + /* Shift all affected entries by 1 to open a hole at idx. */ + r =3D &dev->regions[idx]; + memmove(r + 1, r, sizeof(VuDevRegion) * (dev->nregions - idx)); r->gpa =3D msg_region->guest_phys_addr; r->size =3D msg_region->memory_size; r->qva =3D msg_region->userspace_addr; --=20 2.43.0