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Tue, 04 Jul 2023 01:06:46 -0700 (PDT) Received: from mnissler.ba.rivosinc.com ([66.220.2.162]) by smtp.gmail.com with ESMTPSA id u1-20020aa78381000000b00662c4ca18ebsm15113101pfm.128.2023.07.04.01.06.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Jul 2023 01:06:46 -0700 (PDT) From: Mattias Nissler To: qemu-devel@nongnu.org Cc: Elena Ufimtseva , Jagannathan Raman , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , Paolo Bonzini , Peter Xu , stefanha@redhat.com, David Hildenbrand , john.levon@nutanix.com, Mattias Nissler Subject: [PATCH 1/3] softmmu: Support concurrent bounce buffers Date: Tue, 4 Jul 2023 01:06:25 -0700 Message-Id: <20230704080628.852525-2-mnissler@rivosinc.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230704080628.852525-1-mnissler@rivosinc.com> References: <20230704080628.852525-1-mnissler@rivosinc.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::435; envelope-from=mnissler@rivosinc.com; helo=mail-pf1-x435.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org It is not uncommon for device models to request mapping of several DMA regions at the same time. An example is igb (and probably other net devices as well) when a packet is spread across multiple descriptors. In order to support this when indirect DMA is used, as is the case when running the device model in a vfio-server process without mmap()-ed DMA, this change allocates DMA bounce buffers dynamically instead of supporting only a single buffer. Signed-off-by: Mattias Nissler --- softmmu/physmem.c | 74 ++++++++++++++++++++++------------------------- 1 file changed, 35 insertions(+), 39 deletions(-) diff --git a/softmmu/physmem.c b/softmmu/physmem.c index bda475a719..56130b5a1d 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -2904,13 +2904,11 @@ void cpu_flush_icache_range(hwaddr start, hwaddr len) typedef struct { MemoryRegion *mr; - void *buffer; hwaddr addr; - hwaddr len; - bool in_use; + uint8_t buffer[]; } BounceBuffer; -static BounceBuffer bounce; +static size_t bounce_buffers_in_use; typedef struct MapClient { QEMUBH *bh; @@ -2947,7 +2945,7 @@ void cpu_register_map_client(QEMUBH *bh) QLIST_INSERT_HEAD(&map_client_list, client, link); /* Write map_client_list before reading in_use. */ smp_mb(); - if (!qatomic_read(&bounce.in_use)) { + if (qatomic_read(&bounce_buffers_in_use)) { cpu_notify_map_clients_locked(); } qemu_mutex_unlock(&map_client_list_lock); @@ -3076,31 +3074,24 @@ void *address_space_map(AddressSpace *as, RCU_READ_LOCK_GUARD(); fv = address_space_to_flatview(as); mr = flatview_translate(fv, addr, &xlat, &l, is_write, attrs); + memory_region_ref(mr); if (!memory_access_is_direct(mr, is_write)) { - if (qatomic_xchg(&bounce.in_use, true)) { - *plen = 0; - return NULL; - } - /* Avoid unbounded allocations */ - l = MIN(l, TARGET_PAGE_SIZE); - bounce.buffer = qemu_memalign(TARGET_PAGE_SIZE, l); - bounce.addr = addr; - bounce.len = l; - - memory_region_ref(mr); - bounce.mr = mr; + qatomic_inc_fetch(&bounce_buffers_in_use); + + BounceBuffer *bounce = g_malloc(l + sizeof(BounceBuffer)); + bounce->addr = addr; + bounce->mr = mr; + if (!is_write) { flatview_read(fv, addr, MEMTXATTRS_UNSPECIFIED, - bounce.buffer, l); + bounce->buffer, l); } *plen = l; - return bounce.buffer; + return bounce->buffer; } - - memory_region_ref(mr); *plen = flatview_extend_translation(fv, addr, len, mr, xlat, l, is_write, attrs); fuzz_dma_read_cb(addr, *plen, mr); @@ -3114,31 +3105,36 @@ void *address_space_map(AddressSpace *as, void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len, bool is_write, hwaddr access_len) { - if (buffer != bounce.buffer) { - MemoryRegion *mr; - ram_addr_t addr1; + MemoryRegion *mr; + ram_addr_t addr1; + + mr = memory_region_from_host(buffer, &addr1); + if (mr == NULL) { + /* + * Must be a bounce buffer (unless the caller passed a pointer which + * wasn't returned by address_space_map, which is illegal). + */ + BounceBuffer *bounce = container_of(buffer, BounceBuffer, buffer); - mr = memory_region_from_host(buffer, &addr1); - assert(mr != NULL); if (is_write) { - invalidate_and_set_dirty(mr, addr1, access_len); + address_space_write(as, bounce->addr, MEMTXATTRS_UNSPECIFIED, + bounce->buffer, access_len); } - if (xen_enabled()) { - xen_invalidate_map_cache_entry(buffer); + memory_region_unref(bounce->mr); + g_free(bounce); + + if (qatomic_dec_fetch(&bounce_buffers_in_use) == 1) { + cpu_notify_map_clients(); } - memory_region_unref(mr); return; } + + if (xen_enabled()) { + xen_invalidate_map_cache_entry(buffer); + } if (is_write) { - address_space_write(as, bounce.addr, MEMTXATTRS_UNSPECIFIED, - bounce.buffer, access_len); - } - qemu_vfree(bounce.buffer); - bounce.buffer = NULL; - memory_region_unref(bounce.mr); - /* Clear in_use before reading map_client_list. */ - qatomic_set_mb(&bounce.in_use, false); - cpu_notify_map_clients(); + invalidate_and_set_dirty(mr, addr1, access_len); + } } void *cpu_physical_memory_map(hwaddr addr,