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] [<ffffffffafcf6b3a>] dump_stack+0x19/0x1b [ 1.018334] [<ffffffffaf68fff8>] __warn+0xd8/0x100 [ 1.018336] [<ffffffffaf69007f>] warn_slowpath_fmt+0x5f/0x80 [ 1.018338] [<ffffffffafb67329>] fw_cfg_dma_transfer+0x399/0x500 [ 1.018340] [<ffffffffafb6753c>] fw_cfg_read_blob+0xac/0x1c0 [ 1.018342] [<ffffffffafb67720>] fw_cfg_register_dir_entries+0x80/0x450 [ 1.018344] [<ffffffffafb67d02>] fw_cfg_sysfs_probe+0x212/0x3f0 [ 1.018347] [<ffffffffafa70352>] platform_drv_probe+0x42/0x110 [ 1.018350] [<ffffffffafa6e002>] driver_probe_device+0xc2/0x3e0 [ 1.018352] [<ffffffffafa6e3f3>] __driver_attach+0x93/0xa0 [ 1.018354] [<ffffffffafa6e360>] ? __device_attach+0x40/0x40 [ 1.018359] [<ffffffffafa6bbd3>] bus_for_each_dev+0x73/0xc0 [ 1.018362] [<ffffffffafa6d97e>] driver_attach+0x1e/0x20 [ 1.018364] [<ffffffffafa6d420>] bus_add_driver+0x200/0x2d0 [ 1.018366] [<ffffffffb03c2041>] ? firmware_map_add_early+0x58/0x58 [ 1.018368] [<ffffffffafa6ea84>] driver_register+0x64/0xf0 [ 1.018370] [<ffffffffafa7013a>] __platform_driver_register+0x4a/0x50 [ 1.018372] [<ffffffffb03c2075>] fw_cfg_sysfs_init+0x34/0x61 [ 1.018376] [<ffffffffaf602108>] do_one_initcall+0xb8/0x230 [ 1.018379] [<ffffffffb036b34a>] kernel_init_freeable+0x17a/0x219 [ 1.018381] [<ffffffffb036ab19>] ? initcall_blacklist+0xb0/0xb0 [ 1.018383] [<ffffffffafce5b30>] ? rest_init+0x80/0x80 [ 1.018385] [<ffffffffafce5b3e>] kernel_init+0xe/0xf0 [ 1.018388] [<ffffffffafd08898>] ret_from_fork+0x58/0x90 [ 1.018390] [<ffffffffafce5b30>] ? 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 <marcandre.lur...@redhat.com> CC: Michael S. Tsirkin <m...@redhat.com> Signed-off-by: Peter Xu <pet...@redhat.com> -- 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 <pet...@redhat.com> --- 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
