If the WSMT ACPI table is present and indicates that a fixed communication buffer should be used, use the firmware-specified buffer instead of allocating a buffer in memory for communications between the dcdbas driver and firmare.
Signed-off-by: Stuart Hayes <stuart.w.ha...@gmail.com> Tested-by: Mario Limonciello <mario.limoncie...@dell.com> Acked-by: Doug Warzecha <douglas_warze...@dell.com> --- v2 Bumped driver version to 5.6.0-3.3 drivers/firmware/Kconfig | 2 +- drivers/firmware/dcdbas.c | 102 +++++++++++++++++++++++++++++++++++++++++++--- drivers/firmware/dcdbas.h | 11 +++++ 3 files changed, 109 insertions(+), 6 deletions(-) diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig index b7c748248e53..a2bd6092bfa1 100644 --- a/drivers/firmware/Kconfig +++ b/drivers/firmware/Kconfig @@ -125,7 +125,7 @@ config DELL_RBU config DCDBAS tristate "Dell Systems Management Base Driver" - depends on X86 + depends on X86 && ACPI help The Dell Systems Management Base Driver provides a sysfs interface for systems management software to perform System Management diff --git a/drivers/firmware/dcdbas.c b/drivers/firmware/dcdbas.c index 0bdea60c65dd..1699cfdcefe4 100644 --- a/drivers/firmware/dcdbas.c +++ b/drivers/firmware/dcdbas.c @@ -36,12 +36,13 @@ #include <linux/string.h> #include <linux/types.h> #include <linux/mutex.h> +#include <linux/acpi.h> #include <asm/io.h> #include "dcdbas.h" #define DRIVER_NAME "dcdbas" -#define DRIVER_VERSION "5.6.0-3.2" +#define DRIVER_VERSION "5.6.0-3.3" #define DRIVER_DESCRIPTION "Dell Systems Management Base Driver" static struct platform_device *dcdbas_pdev; @@ -49,19 +50,23 @@ static struct platform_device *dcdbas_pdev; static u8 *smi_data_buf; static dma_addr_t smi_data_buf_handle; static unsigned long smi_data_buf_size; +static unsigned long max_smi_data_buf_size = MAX_SMI_DATA_BUF_SIZE; static u32 smi_data_buf_phys_addr; static DEFINE_MUTEX(smi_data_lock); +static u8 *eps_buffer; static unsigned int host_control_action; static unsigned int host_control_smi_type; static unsigned int host_control_on_shutdown; +static bool wsmt_enabled; + /** * smi_data_buf_free: free SMI data buffer */ static void smi_data_buf_free(void) { - if (!smi_data_buf) + if (!smi_data_buf || wsmt_enabled) return; dev_dbg(&dcdbas_pdev->dev, "%s: phys: %x size: %lu\n", @@ -86,7 +91,7 @@ static int smi_data_buf_realloc(unsigned long size) if (smi_data_buf_size >= size) return 0; - if (size > MAX_SMI_DATA_BUF_SIZE) + if (size > max_smi_data_buf_size) return -EINVAL; /* new buffer is needed */ @@ -169,7 +174,7 @@ static ssize_t smi_data_write(struct file *filp, struct kobject *kobj, { ssize_t ret; - if ((pos + count) > MAX_SMI_DATA_BUF_SIZE) + if ((pos + count) > max_smi_data_buf_size) return -EINVAL; mutex_lock(&smi_data_lock); @@ -323,7 +328,8 @@ static ssize_t smi_request_store(struct device *dev, break; case 1: /* Calling Interface SMI */ - smi_cmd->ebx = (u32) virt_to_phys(smi_cmd->command_buffer); + smi_cmd->ebx = smi_data_buf_phys_addr + + offsetof(struct smi_cmd, command_buffer); ret = dcdbas_smi_request(smi_cmd); if (!ret) ret = count; @@ -482,6 +488,85 @@ static void dcdbas_host_control(void) } } +/* WSMT */ + +static u8 checksum(u8 *buffer, u8 length) +{ + u8 sum = 0; + u8 *end = buffer + length; + + while (buffer < end) + sum = (u8)(sum + *(buffer++)); + return sum; +} + +static inline struct smm_eps_table *check_eps_table(u8 *addr) +{ + struct smm_eps_table *eps = (struct smm_eps_table *)addr; + + if (strncmp(SMM_EPS_SIG, eps->smm_comm_buff_anchor, 4) != 0) + return NULL; + + if (checksum(addr, eps->length) != 0) + return NULL; + + return eps; +} + +static int dcdbas_check_wsmt(void) +{ + struct acpi_table_wsmt *wsmt = NULL; + struct smm_eps_table *eps = NULL; + u8 *addr; + + acpi_get_table(ACPI_SIG_WSMT, 0, (struct acpi_table_header **)&wsmt); + if (!wsmt) + return 0; + + /* Check if WSMT ACPI table shows that protection is enabled */ + if (!(wsmt->protection_flags & ACPI_WSMT_FIXED_COMM_BUFFERS) + || !(wsmt->protection_flags + & ACPI_WSMT_COMM_BUFFER_NESTED_PTR_PROTECTION)) + return 0; + + /* Scan for EPS (entry point structure) */ + for (addr = (u8 *)__va(0xf0000); + addr < (u8 *)__va(0x100000 - sizeof(struct smm_eps_table)) && !eps; + addr += 1) + eps = check_eps_table(addr); + + if (!eps) { + dev_dbg(&dcdbas_pdev->dev, "found WSMT, but no EPS found\n"); + return -ENODEV; + } + + /* + * Get physical address of buffer and map to virtual address. + * Table gives size in 4K pages, regardless of actual system page size. + */ + if (eps->smm_comm_buff_addr + 8 > U32_MAX) { + dev_warn(&dcdbas_pdev->dev, "found WSMT, but EPS buffer address is above 4GB\n"); + return -EINVAL; + } + eps_buffer = (u8 *)memremap(eps->smm_comm_buff_addr, + eps->num_of_4k_pages * 4096, MEMREMAP_WB); + if (!eps_buffer) { + dev_warn(&dcdbas_pdev->dev, "found WSMT, but failed to map EPS buffer\n"); + return -ENOMEM; + } + + /* First 8 bytes of buffer is for semaphore */ + smi_data_buf_phys_addr = (u32) eps->smm_comm_buff_addr + 8; + smi_data_buf = eps_buffer + 8; + smi_data_buf_size = (unsigned long) min(eps->num_of_4k_pages * 4096 - 8, + (u64) ULONG_MAX); + max_smi_data_buf_size = smi_data_buf_size; + wsmt_enabled = true; + dev_info(&dcdbas_pdev->dev, + "WSMT found, using firmware-provided SMI buffer.\n"); + return 1; +} + /** * dcdbas_reboot_notify: handle reboot notification for host control */ @@ -548,6 +633,11 @@ static int dcdbas_probe(struct platform_device *dev) dcdbas_pdev = dev; + /* Check if ACPI WSMT table specifies protected SMI buffer address */ + error = dcdbas_check_wsmt(); + if (error < 0) + return error; + /* * BIOS SMI calls require buffer addresses be in 32-bit address space. * This is done by setting the DMA mask below. @@ -635,6 +725,8 @@ static void __exit dcdbas_exit(void) */ if (dcdbas_pdev) smi_data_buf_free(); + if (eps_buffer) + memunmap(eps_buffer); platform_device_unregister(dcdbas_pdev_reg); platform_driver_unregister(&dcdbas_driver); } diff --git a/drivers/firmware/dcdbas.h b/drivers/firmware/dcdbas.h index ca3cb0a54ab6..7ea5b3e070b9 100644 --- a/drivers/firmware/dcdbas.h +++ b/drivers/firmware/dcdbas.h @@ -54,6 +54,8 @@ #define SMI_CMD_MAGIC (0x534D4931) +#define SMM_EPS_SIG "$SCB" + #define DCDBAS_DEV_ATTR_RW(_name) \ DEVICE_ATTR(_name,0600,_name##_show,_name##_store); @@ -103,5 +105,14 @@ struct apm_cmd { int dcdbas_smi_request(struct smi_cmd *smi_cmd); +struct smm_eps_table { + char smm_comm_buff_anchor[4]; + u8 length; + u8 checksum; + u8 version; + u64 smm_comm_buff_addr; + u64 num_of_4k_pages; +} __packed; + #endif /* _DCDBAS_H_ */ -- 2.14.2