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platform/x86: dcdbas: Check SMBIOS for protected buffer address 

Add support for a new method for BIOS to provide the address and length
of the protected SMI communication buffer, via SMBIOS OEM strings.

Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Stuart Hayes 2020-05-19 11:27:33 -04:00 committed by Andy Shevchenko
parent 30a44f7b80
commit 47a94c551a
1 changed files with 30 additions and 13 deletions
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43
drivers/platform/x86/dcdbas.c
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@ -15,6 +15,7 @@
#include <linux/platform_device.h>
#include <linux/acpi.h>
#include <linux/dma-mapping.h>
#include <linux/dmi.h>
#include <linux/errno.h>
#include <linux/cpu.h>
#include <linux/gfp.h>
@ -34,7 +35,7 @@
#include "dcdbas.h"
#define DRIVER_NAME "dcdbas"
#define DRIVER_VERSION "5.6.0-3.3"
#define DRIVER_VERSION "5.6.0-3.4"
#define DRIVER_DESCRIPTION "Dell Systems Management Base Driver"
static struct platform_device *dcdbas_pdev;
@ -45,7 +46,7 @@ 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 u8 *bios_buffer;
static unsigned int host_control_action;
static unsigned int host_control_smi_type;
@ -518,8 +519,10 @@ static inline struct smm_eps_table *check_eps_table(u8 *addr)
static int dcdbas_check_wsmt(void)
{
const struct dmi_device *dev = NULL;
struct acpi_table_wsmt *wsmt = NULL;
struct smm_eps_table *eps = NULL;
u64 bios_buf_paddr;
u64 remap_size;
u8 *addr;
@ -532,6 +535,17 @@ static int dcdbas_check_wsmt(void)
!(wsmt->protection_flags & ACPI_WSMT_COMM_BUFFER_NESTED_PTR_PROTECTION))
return 0;
/*
* BIOS could provide the address/size of the protected buffer
* in an SMBIOS string or in an EPS structure in 0xFxxxx.
*/
/* Check SMBIOS for buffer address */
while ((dev = dmi_find_device(DMI_DEV_TYPE_OEM_STRING, NULL, dev)))
if (sscanf(dev->name, "30[%16llx;%8llx]", &bios_buf_paddr,
&remap_size) == 2)
goto remap;
/* Scan for EPS (entry point structure) */
for (addr = (u8 *)__va(0xf0000);
addr < (u8 *)__va(0x100000 - sizeof(struct smm_eps_table));
@ -542,34 +556,37 @@ static int dcdbas_check_wsmt(void)
}
if (!eps) {
dev_dbg(&dcdbas_pdev->dev, "found WSMT, but no EPS found\n");
dev_dbg(&dcdbas_pdev->dev, "found WSMT, but no firmware buffer found\n");
return -ENODEV;
}
bios_buf_paddr = eps->smm_comm_buff_addr;
remap_size = eps->num_of_4k_pages * PAGE_SIZE;
remap:
/*
* Get physical address of buffer and map to virtual address.
* Table gives size in 4K pages, regardless of actual system page size.
*/
if (upper_32_bits(eps->smm_comm_buff_addr + 8)) {
dev_warn(&dcdbas_pdev->dev, "found WSMT, but EPS buffer address is above 4GB\n");
if (upper_32_bits(bios_buf_paddr + 8)) {
dev_warn(&dcdbas_pdev->dev, "found WSMT, but buffer address is above 4GB\n");
return -EINVAL;
}
/*
* Limit remap size to MAX_SMI_DATA_BUF_SIZE + 8 (since the first 8
* bytes are used for a semaphore, not the data buffer itself).
*/
remap_size = eps->num_of_4k_pages * PAGE_SIZE;
if (remap_size > MAX_SMI_DATA_BUF_SIZE + 8)
remap_size = MAX_SMI_DATA_BUF_SIZE + 8;
eps_buffer = memremap(eps->smm_comm_buff_addr, remap_size, MEMREMAP_WB);
if (!eps_buffer) {
dev_warn(&dcdbas_pdev->dev, "found WSMT, but failed to map EPS buffer\n");
bios_buffer = memremap(bios_buf_paddr, remap_size, MEMREMAP_WB);
if (!bios_buffer) {
dev_warn(&dcdbas_pdev->dev, "found WSMT, but failed to map buffer\n");
return -ENOMEM;
}
/* First 8 bytes is for a semaphore, not part of the smi_data_buf */
smi_data_buf_phys_addr = eps->smm_comm_buff_addr + 8;
smi_data_buf = eps_buffer + 8;
smi_data_buf_phys_addr = bios_buf_paddr + 8;
smi_data_buf = bios_buffer + 8;
smi_data_buf_size = remap_size - 8;
max_smi_data_buf_size = smi_data_buf_size;
wsmt_enabled = true;
@ -736,8 +753,8 @@ static void __exit dcdbas_exit(void)
*/
if (dcdbas_pdev)
smi_data_buf_free();
if (eps_buffer)
memunmap(eps_buffer);
if (bios_buffer)
memunmap(bios_buffer);
platform_device_unregister(dcdbas_pdev_reg);
platform_driver_unregister(&dcdbas_driver);
}