Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1035940AbdD1Mpx (ORCPT ); Fri, 28 Apr 2017 08:45:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49158 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1034911AbdD1Mpn (ORCPT ); Fri, 28 Apr 2017 08:45:43 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com B253D80F6C Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=marcandre.lureau@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com B253D80F6C From: marcandre.lureau@redhat.com To: qemu-devel@nongnu.org Cc: somlo@cmu.edu, linux-kernel@vger.kernel.org, mst@redhat.com, =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Subject: [PATCH 2/3] fw_cfg: do DMA read operation Date: Fri, 28 Apr 2017 16:45:09 +0400 Message-Id: <20170428124510.23654-3-marcandre.lureau@redhat.com> In-Reply-To: <20170428124510.23654-1-marcandre.lureau@redhat.com> References: <20170428124510.23654-1-marcandre.lureau@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 [10.5.110.27]); Fri, 28 Apr 2017 12:45:42 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7448 Lines: 241 From: Marc-André Lureau Modify fw_cfg_read_blob() to use DMA if the device supports it. Return errors, because the operation may fail. This is a proof-of-concept patch with some FIXME. It uses yield() to wait for the memory to be cleared, and it uses 2 iowrite32() to write a 64bit value. Help on how to improve this is welcome. We may also want to switch the *buf address to use only kmalloc'ed buffer (instead of allowing stack/image addresses with dma=false). Signed-off-by: Marc-André Lureau --- drivers/firmware/qemu_fw_cfg.c | 125 +++++++++++++++++++++++++++++++++++------ 1 file changed, 109 insertions(+), 16 deletions(-) diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c index 614037703530..430289332c95 100644 --- a/drivers/firmware/qemu_fw_cfg.c +++ b/drivers/firmware/qemu_fw_cfg.c @@ -33,6 +33,7 @@ #include #include #include +#include MODULE_AUTHOR("Gabriel L. Somlo "); MODULE_DESCRIPTION("QEMU fw_cfg sysfs support"); @@ -43,12 +44,22 @@ MODULE_LICENSE("GPL"); #define FW_CFG_ID 0x01 #define FW_CFG_FILE_DIR 0x19 +#define FW_CFG_VERSION_DMA 2 +#define FW_CFG_DMA_CTL_ERROR 0x01 +#define FW_CFG_DMA_CTL_READ 0x02 +#define FW_CFG_DMA_CTL_SKIP 0x04 +#define FW_CFG_DMA_CTL_SELECT 0x08 +#define FW_CFG_DMA_CTL_WRITE 0x10 + /* size in bytes of fw_cfg signature */ #define FW_CFG_SIG_SIZE 4 /* fw_cfg "file name" is up to 56 characters (including terminating nul) */ #define FW_CFG_MAX_FILE_PATH 56 +/* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */ +static u32 fw_cfg_rev; + /* fw_cfg file directory entry type */ struct fw_cfg_file { u32 size; @@ -57,6 +68,12 @@ struct fw_cfg_file { char name[FW_CFG_MAX_FILE_PATH]; }; +struct fw_cfg_dma { + u32 control; + u32 length; + u64 address; +} __packed; + /* fw_cfg device i/o register addresses */ static bool fw_cfg_is_mmio; static phys_addr_t fw_cfg_p_base; @@ -75,12 +92,73 @@ static inline u16 fw_cfg_sel_endianness(u16 key) return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key); } +static inline bool fw_cfg_dma_enabled(void) +{ + return fw_cfg_rev & FW_CFG_VERSION_DMA && fw_cfg_reg_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; + dma_addr_t dma; + ssize_t ret = length; + enum dma_data_direction dir = + (control & FW_CFG_DMA_CTL_READ ? DMA_FROM_DEVICE : 0); + + if (address && length) { + dma_addr = dma_map_single(NULL, address, length, dir); + if (dma_mapping_error(NULL, dma_addr)) { + WARN(1, "fw_cfg_dma_transfer: failed to map address\n"); + return -EFAULT; + } + } + + d = kmalloc(sizeof(*d), GFP_KERNEL | GFP_DMA); + if (!d) { + ret = -ENOMEM; + goto end; + } + + dma = dma_map_single(NULL, d, sizeof(*d), DMA_BIDIRECTIONAL); + if (dma_mapping_error(NULL, dma)) { + WARN(1, "fw_cfg_dma_transfer: failed to map fw_cfg_dma\n"); + ret = -EFAULT; + goto end; + } + + *d = (struct fw_cfg_dma) { + .address = cpu_to_be64(dma_addr), + .length = cpu_to_be32(length), + .control = cpu_to_be32(control) + }; + /* fixme: no iowrite64? */ + iowrite32(cpu_to_be32(dma >> 32), fw_cfg_reg_dma); + iowrite32(cpu_to_be32(dma), fw_cfg_reg_dma + 4); + while (be32_to_cpu(d->control) & ~FW_CFG_DMA_CTL_ERROR) + yield(); /* fixme: wait_event? */ + + if (be32_to_cpu(d->control) & FW_CFG_DMA_CTL_ERROR) + ret = -EIO; + + dma_unmap_single(NULL, dma, sizeof(*d), DMA_BIDIRECTIONAL); + +end: + kfree(d); + if (dma_addr) + dma_unmap_single(NULL, dma_addr, length, dir); + + return ret; +} + /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */ -static inline void fw_cfg_read_blob(u16 key, - void *buf, loff_t pos, size_t count) +static ssize_t fw_cfg_read_blob(u16 key, + void *buf, loff_t pos, size_t count, + bool dma) { u32 glk = -1U; acpi_status status; + ssize_t ret = count; /* If we have ACPI, ensure mutual exclusion against any potential * device access by the firmware, e.g. via AML methods: @@ -90,17 +168,36 @@ static inline void fw_cfg_read_blob(u16 key, /* Should never get here */ WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n"); memset(buf, 0, count); - return; + return -EBUSY; } mutex_lock(&fw_cfg_dev_lock); - iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl); - while (pos-- > 0) - ioread8(fw_cfg_reg_data); - ioread8_rep(fw_cfg_reg_data, buf, count); + if (dma && fw_cfg_dma_enabled()) { + if (pos == 0) { + ret = fw_cfg_dma_transfer(buf, count, key << 16 + | FW_CFG_DMA_CTL_SELECT + | FW_CFG_DMA_CTL_READ); + } else { + iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl); + ret = fw_cfg_dma_transfer(0, pos, FW_CFG_DMA_CTL_SKIP); + if (ret < 0) + goto end; + ret = fw_cfg_dma_transfer(buf, count, + FW_CFG_DMA_CTL_READ); + } + } else { + iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl); + while (pos-- > 0) + ioread8(fw_cfg_reg_data); + ioread8_rep(fw_cfg_reg_data, buf, count); + } + +end: mutex_unlock(&fw_cfg_dev_lock); acpi_release_global_lock(glk); + + return ret; } /* clean up fw_cfg device i/o */ @@ -192,7 +289,7 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev) #endif /* verify fw_cfg device signature */ - fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE); + fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE, false); if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) { fw_cfg_io_cleanup(); return -ENODEV; @@ -201,9 +298,6 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev) return 0; } -/* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */ -static u32 fw_cfg_rev; - static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf) { return sprintf(buf, "%u\n", fw_cfg_rev); @@ -351,8 +445,7 @@ static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj, if (count > entry->f.size - pos) count = entry->f.size - pos; - fw_cfg_read_blob(entry->f.select, buf, pos, count); - return count; + return fw_cfg_read_blob(entry->f.select, buf, pos, count, true); } static struct bin_attribute fw_cfg_sysfs_attr_raw = { @@ -505,7 +598,7 @@ static int fw_cfg_register_dir_entries(void) struct fw_cfg_file *dir; size_t dir_size; - fw_cfg_read_blob(FW_CFG_FILE_DIR, &count, 0, sizeof(count)); + fw_cfg_read_blob(FW_CFG_FILE_DIR, &count, 0, sizeof(count), false); count = be32_to_cpu(count); dir_size = count * sizeof(struct fw_cfg_file); @@ -513,7 +606,7 @@ static int fw_cfg_register_dir_entries(void) if (!dir) return -ENOMEM; - fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(count), dir_size); + fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(count), dir_size, true); for (i = 0; i < count; i++) { dir[i].size = be32_to_cpu(dir[i].size); @@ -562,7 +655,7 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev) goto err_probe; /* get revision number, add matching top-level attribute */ - fw_cfg_read_blob(FW_CFG_ID, &fw_cfg_rev, 0, sizeof(fw_cfg_rev)); + fw_cfg_read_blob(FW_CFG_ID, &fw_cfg_rev, 0, sizeof(fw_cfg_rev), false); fw_cfg_rev = le32_to_cpu(fw_cfg_rev); err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr); if (err) -- 2.12.0.191.gc5d8de91d