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Subject[PATCH 1/2] x86/microcode: Attempt late loading only when new microcode is present
Date
From: Borislav Petkov <bp@suse.de>

Return UCODE_NEW from the scanning functions to denote that new
microcode was found and only then attempt the expensive synchronization
dance.

Reported-and-tested-by: Emanuel Czirai <xftroxgpx@protonmail.com>
Tested-by: Ashok Raj <ashok.raj@intel.com>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/include/asm/microcode.h | 1 +
arch/x86/kernel/cpu/microcode/amd.c | 34 +++++++++++++++++++++-------------
arch/x86/kernel/cpu/microcode/core.c | 8 +++-----
arch/x86/kernel/cpu/microcode/intel.c | 4 +++-
4 files changed, 28 insertions(+), 19 deletions(-)

diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index 871714e2e4c6..2b7cc5397f80 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -25,6 +25,7 @@ struct device;

enum ucode_state {
UCODE_OK = 0,
+ UCODE_NEW,
UCODE_UPDATED,
UCODE_NFOUND,
UCODE_ERROR,
diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index a998e1a7d46f..48179928ff38 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -339,7 +339,7 @@ int __init save_microcode_in_initrd_amd(unsigned int cpuid_1_eax)
return -EINVAL;

ret = load_microcode_amd(true, x86_family(cpuid_1_eax), desc.data, desc.size);
- if (ret != UCODE_OK)
+ if (ret > UCODE_UPDATED)
return -EINVAL;

return 0;
@@ -683,27 +683,35 @@ static enum ucode_state __load_microcode_amd(u8 family, const u8 *data,
static enum ucode_state
load_microcode_amd(bool save, u8 family, const u8 *data, size_t size)
{
+ struct ucode_patch *p;
enum ucode_state ret;

/* free old equiv table */
free_equiv_cpu_table();

ret = __load_microcode_amd(family, data, size);
-
- if (ret != UCODE_OK)
+ if (ret != UCODE_OK) {
cleanup();
+ return ret;
+ }

-#ifdef CONFIG_X86_32
- /* save BSP's matching patch for early load */
- if (save) {
- struct ucode_patch *p = find_patch(0);
- if (p) {
- memset(amd_ucode_patch, 0, PATCH_MAX_SIZE);
- memcpy(amd_ucode_patch, p->data, min_t(u32, ksize(p->data),
- PATCH_MAX_SIZE));
- }
+ p = find_patch(0);
+ if (!p) {
+ return ret;
+ } else {
+ if (boot_cpu_data.microcode == p->patch_id)
+ return ret;
+
+ ret = UCODE_NEW;
}
-#endif
+
+ /* save BSP's matching patch for early load */
+ if (!save)
+ return ret;
+
+ memset(amd_ucode_patch, 0, PATCH_MAX_SIZE);
+ memcpy(amd_ucode_patch, p->data, min_t(u32, ksize(p->data), PATCH_MAX_SIZE));
+
return ret;
}

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 70ecbc8099c9..9f0fe5bb450d 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -607,7 +607,7 @@ static ssize_t reload_store(struct device *dev,
return size;

tmp_ret = microcode_ops->request_microcode_fw(bsp, &microcode_pdev->dev, true);
- if (tmp_ret != UCODE_OK)
+ if (tmp_ret != UCODE_NEW)
return size;

get_online_cpus();
@@ -691,10 +691,8 @@ static enum ucode_state microcode_init_cpu(int cpu, bool refresh_fw)
if (system_state != SYSTEM_RUNNING)
return UCODE_NFOUND;

- ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev,
- refresh_fw);
-
- if (ustate == UCODE_OK) {
+ ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev, refresh_fw);
+ if (ustate == UCODE_NEW) {
pr_debug("CPU%d updated upon init\n", cpu);
apply_microcode_on_target(cpu);
}
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 2aded9db1d42..32b8e5724f96 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -862,6 +862,7 @@ static enum ucode_state generic_load_microcode(int cpu, void *data, size_t size,
unsigned int leftover = size;
unsigned int curr_mc_size = 0, new_mc_size = 0;
unsigned int csig, cpf;
+ enum ucode_state ret = UCODE_OK;

while (leftover) {
struct microcode_header_intel mc_header;
@@ -903,6 +904,7 @@ static enum ucode_state generic_load_microcode(int cpu, void *data, size_t size,
new_mc = mc;
new_mc_size = mc_size;
mc = NULL; /* trigger new vmalloc */
+ ret = UCODE_NEW;
}

ucode_ptr += mc_size;
@@ -932,7 +934,7 @@ static enum ucode_state generic_load_microcode(int cpu, void *data, size_t size,
pr_debug("CPU%d found a matching microcode update with version 0x%x (current=0x%x)\n",
cpu, new_rev, uci->cpu_sig.rev);

- return UCODE_OK;
+ return ret;
}

static int get_ucode_fw(void *to, const void *from, size_t n)
--
2.13.0
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