[tip:x86/microcode] x86, microcode, AMD: Rewrite patch application procedure

From: tip-bot for Borislav Petkov
Date: Wed Aug 22 2012 - 19:47:02 EST

Commit-ID: 2efb05e8e9fa3510044e007b90263c73b6a83f84
Gitweb: http://git.kernel.org/tip/2efb05e8e9fa3510044e007b90263c73b6a83f84
Author: Borislav Petkov <borislav.petkov@xxxxxxx>
AuthorDate: Wed, 1 Aug 2012 16:16:13 +0200
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Wed, 22 Aug 2012 16:16:29 -0700

x86, microcode, AMD: Rewrite patch application procedure

Limit the access to userspace only on the BSP where we load the
container, verify the patches in it and put them in the patch cache.
Then, at application time, we lookup the correct patch in the cache and
use it.

When we need to reload the userspace container, we do that over the
reload interface:

echo 1 > /sys/devices/system/cpu/microcode/reload

which reloads (a possibly newer) container from userspace and applies
then the newest patches from there.

Signed-off-by: Borislav Petkov <borislav.petkov@xxxxxxx>
Link: http://lkml.kernel.org/r/1344361461-10076-13-git-send-email-bp@xxxxxxxxx
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
arch/x86/kernel/microcode_amd.c | 236 ++++++++++++++++++++-------------------
1 files changed, 121 insertions(+), 115 deletions(-)

diff --git a/arch/x86/kernel/microcode_amd.c b/arch/x86/kernel/microcode_amd.c
index cacdc9a..5511216 100644
--- a/arch/x86/kernel/microcode_amd.c
+++ b/arch/x86/kernel/microcode_amd.c
@@ -75,9 +75,6 @@ struct microcode_amd {

static struct equiv_cpu_entry *equiv_cpu_table;

-/* page-sized ucode patch buffer */
-void *patch;
-
struct ucode_patch {
struct list_head plist;
void *data;
@@ -184,7 +181,7 @@ static int collect_cpu_info_amd(int cpu, struct cpu_signature *csig)
return 0;
}

-static unsigned int verify_ucode_size(int cpu, u32 patch_size,
+static unsigned int verify_patch_size(int cpu, u32 patch_size,
unsigned int size)
{
struct cpuinfo_x86 *c = &cpu_data(cpu);
@@ -214,73 +211,25 @@ static unsigned int verify_ucode_size(int cpu, u32 patch_size,
return patch_size;
}

-/*
- * we signal a good patch is found by returning its size > 0
- */
-static int get_matching_microcode(int cpu, const u8 *ucode_ptr,
- unsigned int leftover_size, int rev,
- unsigned int *current_size)
-{
- struct microcode_header_amd *mc_hdr;
- unsigned int actual_size, patch_size;
- u16 equiv_cpu_id;
-
- /* size of the current patch we're staring at */
- patch_size = *(u32 *)(ucode_ptr + 4);
- *current_size = patch_size + SECTION_HDR_SIZE;
-
- equiv_cpu_id = find_equiv_id(cpu);
- if (!equiv_cpu_id)
- return 0;
-
- /*
- * let's look at the patch header itself now
- */
- mc_hdr = (struct microcode_header_amd *)(ucode_ptr + SECTION_HDR_SIZE);
-
- if (mc_hdr->processor_rev_id != equiv_cpu_id)
- return 0;
-
- /* ucode might be chipset specific -- currently we don't support this */
- if (mc_hdr->nb_dev_id || mc_hdr->sb_dev_id) {
- pr_err("CPU%d: chipset specific code not yet supported\n",
- cpu);
- return 0;
- }
-
- if (mc_hdr->patch_id <= rev)
- return 0;
-
- /*
- * now that the header looks sane, verify its size
- */
- actual_size = verify_ucode_size(cpu, patch_size, leftover_size);
- if (!actual_size)
- return 0;
-
- /* clear the patch buffer */
- memset(patch, 0, PAGE_SIZE);
-
- /* all looks ok, get the binary patch */
- memcpy(patch, ucode_ptr + SECTION_HDR_SIZE, actual_size);
-
- return actual_size;
-}
-
static int apply_microcode_amd(int cpu)
{
- u32 rev, dummy;
- int cpu_num = raw_smp_processor_id();
- struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
- struct microcode_amd *mc_amd = uci->mc;
struct cpuinfo_x86 *c = &cpu_data(cpu);
+ struct microcode_amd *mc_amd;
+ struct ucode_cpu_info *uci;
+ struct ucode_patch *p;
+ u32 rev, dummy;
+
+ BUG_ON(raw_smp_processor_id() != cpu);

- /* We should bind the task to the CPU */
- BUG_ON(cpu_num != cpu);
+ uci = ucode_cpu_info + cpu;

- if (mc_amd == NULL)
+ p = find_patch(cpu);
+ if (!p)
return 0;

+ mc_amd = p->data;
+ uci->mc = p->data;
+
rdmsr(MSR_AMD64_PATCH_LEVEL, rev, dummy);

/* need to apply patch? */
@@ -336,61 +285,113 @@ static void free_equiv_cpu_table(void)
equiv_cpu_table = NULL;
}

-static enum ucode_state
-generic_load_microcode(int cpu, const u8 *data, size_t size)
+static void cleanup(void)
{
- struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
- struct microcode_header_amd *mc_hdr = NULL;
- unsigned int mc_size, leftover, current_size = 0;
+ free_equiv_cpu_table();
+ free_cache();
+}
+
+/*
+ * We return the current size even if some of the checks failed so that
+ * we can skip over the next patch. If we return a negative value, we
+ * signal a grave error like a memory allocation has failed and the
+ * driver cannot continue functioning normally. In such cases, we tear
+ * down everything we've used up so far and exit.
+ */
+static int verify_and_add_patch(unsigned int cpu, u8 *fw, unsigned int leftover)
+{
+ struct cpuinfo_x86 *c = &cpu_data(cpu);
+ struct microcode_header_amd *mc_hdr;
+ struct ucode_patch *patch;
+ unsigned int patch_size, crnt_size, ret;
+ u32 proc_fam;
+ u16 proc_id;
+
+ patch_size = *(u32 *)(fw + 4);
+ crnt_size = patch_size + SECTION_HDR_SIZE;
+ mc_hdr = (struct microcode_header_amd *)(fw + SECTION_HDR_SIZE);
+ proc_id = mc_hdr->processor_rev_id;
+
+ proc_fam = find_cpu_family_by_equiv_cpu(proc_id);
+ if (!proc_fam) {
+ pr_err("No patch family for equiv ID: 0x%04x\n", proc_id);
+ return crnt_size;
+ }
+
+ /* check if patch is for the current family */
+ proc_fam = ((proc_fam >> 8) & 0xf) + ((proc_fam >> 20) & 0xff);
+ if (proc_fam != c->x86)
+ return crnt_size;
+
+ if (mc_hdr->nb_dev_id || mc_hdr->sb_dev_id) {
+ pr_err("Patch-ID 0x%08x: chipset-specific code unsupported.\n",
+ mc_hdr->patch_id);
+ return crnt_size;
+ }
+
+ ret = verify_patch_size(cpu, patch_size, leftover);
+ if (!ret) {
+ pr_err("Patch-ID 0x%08x: size mismatch.\n", mc_hdr->patch_id);
+ return crnt_size;
+ }
+
+ patch = kzalloc(sizeof(*patch), GFP_KERNEL);
+ if (!patch) {
+ pr_err("Patch allocation failure.\n");
+ return -EINVAL;
+ }
+
+ patch->data = kzalloc(patch_size, GFP_KERNEL);
+ if (!patch->data) {
+ pr_err("Patch data allocation failure.\n");
+ kfree(patch);
+ return -EINVAL;
+ }
+
+ /* All looks ok, copy patch... */
+ memcpy(patch->data, fw + SECTION_HDR_SIZE, patch_size);
+ INIT_LIST_HEAD(&patch->plist);
+ patch->patch_id = mc_hdr->patch_id;
+ patch->equiv_cpu = proc_id;
+
+ /* ... and add to cache. */
+ update_cache(patch);
+
+ return crnt_size;
+}
+
+static enum ucode_state load_microcode_amd(int cpu, const u8 *data, size_t size)
+{
+ enum ucode_state ret = UCODE_ERROR;
+ unsigned int leftover;
+ u8 *fw = (u8 *)data;
+ int crnt_size = 0;
int offset;
- const u8 *ucode_ptr = data;
- void *new_mc = NULL;
- unsigned int new_rev = uci->cpu_sig.rev;
- enum ucode_state state = UCODE_ERROR;

- offset = install_equiv_cpu_table(ucode_ptr);
+ offset = install_equiv_cpu_table(data);
if (offset < 0) {
pr_err("failed to create equivalent cpu table\n");
- goto out;
+ return ret;
}
- ucode_ptr += offset;
+ fw += offset;
leftover = size - offset;

- if (*(u32 *)ucode_ptr != UCODE_UCODE_TYPE) {
+ if (*(u32 *)fw != UCODE_UCODE_TYPE) {
pr_err("invalid type field in container file section header\n");
- goto free_table;
+ free_equiv_cpu_table();
+ return ret;
}

while (leftover) {
- mc_size = get_matching_microcode(cpu, ucode_ptr, leftover,
- new_rev, &current_size);
- if (mc_size) {
- mc_hdr = patch;
- new_mc = patch;
- new_rev = mc_hdr->patch_id;
- goto out_ok;
- }
+ crnt_size = verify_and_add_patch(cpu, fw, leftover);
+ if (crnt_size < 0)
+ return ret;

- ucode_ptr += current_size;
- leftover -= current_size;
+ fw += crnt_size;
+ leftover -= crnt_size;
}

- if (!new_mc) {
- state = UCODE_NFOUND;
- goto free_table;
- }
-
-out_ok:
- uci->mc = new_mc;
- state = UCODE_OK;
- pr_debug("CPU%d update ucode (0x%08x -> 0x%08x)\n",
- cpu, uci->cpu_sig.rev, new_rev);
-
-free_table:
- free_equiv_cpu_table();
-
-out:
- return state;
+ return UCODE_OK;
}

/*
@@ -401,7 +402,7 @@ out:
*
* This legacy file is always smaller than 2K in size.
*
- * Starting at family 15h they are in family specific firmware files:
+ * Beginning with family 15h, they are in family-specific firmware files:
*
* amd-ucode/microcode_amd_fam15h.bin
* amd-ucode/microcode_amd_fam16h.bin
@@ -413,9 +414,13 @@ static enum ucode_state request_microcode_amd(int cpu, struct device *device,
bool refresh_fw)
{
char fw_name[36] = "amd-ucode/microcode_amd.bin";
- const struct firmware *fw;
- enum ucode_state ret = UCODE_NFOUND;
struct cpuinfo_x86 *c = &cpu_data(cpu);
+ enum ucode_state ret = UCODE_NFOUND;
+ const struct firmware *fw;
+
+ /* reload ucode container only on the boot cpu */
+ if (!refresh_fw || c->cpu_index != boot_cpu_data.cpu_index)
+ return UCODE_OK;

if (c->x86 >= 0x15)
snprintf(fw_name, sizeof(fw_name), "amd-ucode/microcode_amd_fam%.2xh.bin", c->x86);
@@ -431,12 +436,17 @@ static enum ucode_state request_microcode_amd(int cpu, struct device *device,
goto fw_release;
}

- ret = generic_load_microcode(cpu, fw->data, fw->size);
+ /* free old equiv table */
+ free_equiv_cpu_table();
+
+ ret = load_microcode_amd(cpu, fw->data, fw->size);
+ if (ret != UCODE_OK)
+ cleanup();

-fw_release:
+ fw_release:
release_firmware(fw);

-out:
+ out:
return ret;
}

@@ -470,14 +480,10 @@ struct microcode_ops * __init init_amd_microcode(void)
return NULL;
}

- patch = (void *)get_zeroed_page(GFP_KERNEL);
- if (!patch)
- return NULL;
-
return &microcode_amd_ops;
}

void __exit exit_amd_microcode(void)
{
- free_page((unsigned long)patch);
+ cleanup();
}
--
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