Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932447AbeAOIzk (ORCPT + 1 other); Mon, 15 Jan 2018 03:55:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36288 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932200AbeAOIzj (ORCPT ); Mon, 15 Jan 2018 03:55:39 -0500 From: Peter Xu To: qemu-devel@nongnu.org, Linux Kernel Mailing List Cc: "Michael S . Tsirkin" , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Baoquan He , peterx@redhat.com Subject: [PATCH] fw_cfg: don't use DMA mapping for fw_cfg device Date: Mon, 15 Jan 2018 16:55:28 +0800 Message-Id: <20180115085528.32663-1-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Mon, 15 Jan 2018 08:55:39 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: fw_cfg device does not need IOMMU protection, so use physical addresses always. That's how QEMU implements fw_cfg. Otherwise we'll see call traces during boot when vIOMMU is enabled in guest: [ 1.018306] ------------[ cut here ]------------ [ 1.018314] WARNING: CPU: 1 PID: 1 at drivers/firmware/qemu_fw_cfg.c:152 fw_cfg_dma_transfer+0x399/0x500 [ 1.018315] fw_cfg_dma_transfer: failed to map fw_cfg_dma [ 1.018316] Modules linked in: [ 1.018320] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 3.10.0-827.el7.x86_64 #1 [ 1.018321] Hardware name: Red Hat KVM, BIOS 1.11.0-1.el7 04/01/2014 [ 1.018322] Call Trace: [ 1.018330] [] dump_stack+0x19/0x1b [ 1.018334] [] __warn+0xd8/0x100 [ 1.018336] [] warn_slowpath_fmt+0x5f/0x80 [ 1.018338] [] fw_cfg_dma_transfer+0x399/0x500 [ 1.018340] [] fw_cfg_read_blob+0xac/0x1c0 [ 1.018342] [] fw_cfg_register_dir_entries+0x80/0x450 [ 1.018344] [] fw_cfg_sysfs_probe+0x212/0x3f0 [ 1.018347] [] platform_drv_probe+0x42/0x110 [ 1.018350] [] driver_probe_device+0xc2/0x3e0 [ 1.018352] [] __driver_attach+0x93/0xa0 [ 1.018354] [] ? __device_attach+0x40/0x40 [ 1.018359] [] bus_for_each_dev+0x73/0xc0 [ 1.018362] [] driver_attach+0x1e/0x20 [ 1.018364] [] bus_add_driver+0x200/0x2d0 [ 1.018366] [] ? firmware_map_add_early+0x58/0x58 [ 1.018368] [] driver_register+0x64/0xf0 [ 1.018370] [] __platform_driver_register+0x4a/0x50 [ 1.018372] [] fw_cfg_sysfs_init+0x34/0x61 [ 1.018376] [] do_one_initcall+0xb8/0x230 [ 1.018379] [] kernel_init_freeable+0x17a/0x219 [ 1.018381] [] ? initcall_blacklist+0xb0/0xb0 [ 1.018383] [] ? rest_init+0x80/0x80 [ 1.018385] [] kernel_init+0xe/0xf0 [ 1.018388] [] ret_from_fork+0x58/0x90 [ 1.018390] [] ? rest_init+0x80/0x80 [ 1.018392] ---[ end trace d00a5b71608a8f59 ]--- Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1533367 Fixes: e90cb816599b ("fw_cfg: do DMA read operation", 2017-11-28) CC: Marc-André Lureau CC: Michael S. Tsirkin Signed-off-by: Peter Xu -- This is based on tree: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=vhost Please review, thanks. Signed-off-by: Peter Xu --- drivers/firmware/qemu_fw_cfg.c | 37 ++++++++----------------------------- 1 file changed, 8 insertions(+), 29 deletions(-) diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c index 6eb5d8f43c3e..62a44bc81a88 100644 --- a/drivers/firmware/qemu_fw_cfg.c +++ b/drivers/firmware/qemu_fw_cfg.c @@ -106,11 +106,12 @@ static inline bool fw_cfg_dma_enabled(void) } /* qemu fw_cfg device is sync today, but spec says it may become async */ -static void fw_cfg_wait_for_control(struct fw_cfg_dma *d, dma_addr_t dma) +static void fw_cfg_wait_for_control(struct fw_cfg_dma *d) { do { - dma_sync_single_for_cpu(dev, dma, sizeof(*d), DMA_FROM_DEVICE); - if ((be32_to_cpu(d->control) & ~FW_CFG_DMA_CTL_ERROR) == 0) + u32 ctrl = be32_to_cpu(READ_ONCE(d->control)); + + if ((ctrl & ~FW_CFG_DMA_CTL_ERROR) == 0) return; usleep_range(50, 100); @@ -119,21 +120,9 @@ static void fw_cfg_wait_for_control(struct fw_cfg_dma *d, dma_addr_t dma) static ssize_t fw_cfg_dma_transfer(void *address, u32 length, u32 control) { - dma_addr_t dma_addr = 0; struct fw_cfg_dma *d = NULL; - dma_addr_t dma; ssize_t ret = length; - enum dma_data_direction dir = - (control & FW_CFG_DMA_CTL_READ ? DMA_FROM_DEVICE : 0) | - (control & FW_CFG_DMA_CTL_WRITE ? DMA_TO_DEVICE : 0); - - if (address && length) { - dma_addr = dma_map_single(dev, address, length, dir); - if (dma_mapping_error(NULL, dma_addr)) { - WARN(1, "%s: failed to map address\n", __func__); - return -EFAULT; - } - } + phys_addr_t dma; d = kmalloc(sizeof(*d), GFP_KERNEL); if (!d) { @@ -142,34 +131,24 @@ static ssize_t fw_cfg_dma_transfer(void *address, u32 length, u32 control) } *d = (struct fw_cfg_dma) { - .address = cpu_to_be64(dma_addr), + .address = cpu_to_be64(virt_to_phys(address)), .length = cpu_to_be32(length), .control = cpu_to_be32(control) }; - dma = dma_map_single(dev, d, sizeof(*d), DMA_BIDIRECTIONAL); - if (dma_mapping_error(NULL, dma)) { - WARN(1, "%s: failed to map fw_cfg_dma\n", __func__); - ret = -EFAULT; - goto end; - } + dma = virt_to_phys(d); iowrite32be((u64)dma >> 32, fw_cfg_reg_dma); iowrite32be(dma, fw_cfg_reg_dma + 4); - fw_cfg_wait_for_control(d, dma); + fw_cfg_wait_for_control(d); if (be32_to_cpu(d->control) & FW_CFG_DMA_CTL_ERROR) { ret = -EIO; } - dma_unmap_single(dev, dma, sizeof(*d), DMA_BIDIRECTIONAL); - end: kfree(d); - if (dma_addr) - dma_unmap_single(dev, dma_addr, length, dir); - return ret; } -- 2.14.3