[Xen-devel] [PATCH v5 3/8] microcode: introduce the global microcode cache

[Chao Gao <chao.gao@xxxxxxxxx>]

to replace the current per-cpu cache 'uci->mc'.

Compared to the current per-cpu cache, the benefits of the global
microcode cache are:
1. It reduces the work that need to be done on each CPU. Parsing ucode
file can be done once on one CPU. Other CPUs needn't parse ucode file.
Instead, they can find out and load a patch with newer revision from
the global cache.
2. It reduces the memory consumption on a system with many CPU cores.

Two functions, save_patch() and find_patch() are introduced. The
former adds one given patch to the global cache. The latter gets
a newer and matched ucode patch from the global cache.

Note that I deliberately avoid touching 'uci->mc' as I am going to
remove it completely in the next patch.

Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
---
Changes in v5:
 - reword the commit description
 - find_patch() and save_patch() are abstracted into common functions
   with some hooks for AMD and Intel
---
 xen/arch/x86/microcode.c        | 54 +++++++++++++++++++++++
 xen/arch/x86/microcode_amd.c    | 94 ++++++++++++++++++++++++++++++++++++++---
 xen/arch/x86/microcode_intel.c  | 71 ++++++++++++++++++++++++++++---
 xen/include/asm-x86/microcode.h | 13 ++++++
 4 files changed, 219 insertions(+), 13 deletions(-)

diff --git a/xen/arch/x86/microcode.c b/xen/arch/x86/microcode.c
index 4163f50..7d5b769 100644
--- a/xen/arch/x86/microcode.c
+++ b/xen/arch/x86/microcode.c
@@ -61,6 +61,8 @@ static struct ucode_mod_blob __initdata ucode_blob;
  */
 static bool_t __initdata ucode_scan;
 
+static LIST_HEAD(microcode_cache);
+
 void __init microcode_set_module(unsigned int idx)
 {
     ucode_mod_idx = idx;
@@ -208,6 +210,58 @@ static void microcode_fini_cpu(unsigned int cpu)
     spin_unlock(&microcode_mutex);
 }
 
+/* Save a ucode patch to the global cache list */
+bool save_patch(struct microcode_patch *new_patch)
+{
+    struct microcode_patch *microcode_patch;
+
+    list_for_each_entry(microcode_patch, &microcode_cache, list)
+    {
+        enum microcode_match_result result =
+            microcode_ops->replace_patch(new_patch, microcode_patch);
+
+        switch ( result )
+        {
+        case OLD_UCODE:
+            microcode_ops->free_patch(new_patch);
+            return false;
+
+        case NEW_UCODE:
+            microcode_ops->free_patch(microcode_patch);
+            return true;
+
+        case MIS_UCODE:
+            continue;
+
+        default:
+            ASSERT_UNREACHABLE();
+            return 0;
+        }
+    }
+    list_add_tail(&new_patch->list, &microcode_cache);
+    return true;
+}
+
+/* Find a ucode patch who has newer revision than the one in use */
+struct microcode_patch *find_patch(unsigned int cpu)
+{
+    struct microcode_patch *microcode_patch;
+    struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu);
+
+    if ( microcode_ops->collect_cpu_info(cpu, &uci->cpu_sig) )
+    {
+        __microcode_fini_cpu(cpu);
+        return NULL;
+    }
+
+    list_for_each_entry(microcode_patch, &microcode_cache, list)
+    {
+        if ( microcode_ops->match_cpu(microcode_patch, cpu) )
+            return microcode_patch;
+    }
+    return NULL;
+}
+
 int microcode_resume_cpu(unsigned int cpu)
 {
     int err;
diff --git a/xen/arch/x86/microcode_amd.c b/xen/arch/x86/microcode_amd.c
index fba44cc..301acb6 100644
--- a/xen/arch/x86/microcode_amd.c
+++ b/xen/arch/x86/microcode_amd.c
@@ -190,24 +190,90 @@ static bool_t microcode_fits(const struct microcode_amd 
*mc_amd,
     return 1;
 }
 
+static bool match_cpu(const struct microcode_patch *patch, unsigned int cpu)
+{
+    return microcode_fits(patch->data, cpu);
+}
+
+static struct microcode_patch *alloc_microcode_patch(
+    const struct microcode_amd *mc_amd)
+{
+    struct microcode_patch *microcode_patch = xmalloc(struct microcode_patch);
+    struct microcode_amd *cache = xmalloc(struct microcode_amd);
+    void *mpb = xmalloc_bytes(mc_amd->mpb_size);
+    struct equiv_cpu_entry *equiv_cpu_table =
+                                xmalloc_bytes(mc_amd->equiv_cpu_table_size);
+
+    if ( !microcode_patch || !cache || !mpb || !equiv_cpu_table )
+    {
+        xfree(microcode_patch);
+        xfree(cache);
+        xfree(mpb);
+        xfree(equiv_cpu_table);
+        printk(XENLOG_ERR "microcode: Can not allocate memory\n");
+        return ERR_PTR(-ENOMEM);
+    }
+
+    cache->equiv_cpu_table = equiv_cpu_table;
+    cache->mpb = mpb;
+    memcpy(cache->equiv_cpu_table, mc_amd->equiv_cpu_table,
+           mc_amd->equiv_cpu_table_size);
+    memcpy(cache->mpb, mc_amd->mpb, mc_amd->mpb_size);
+    cache->equiv_cpu_table_size = mc_amd->equiv_cpu_table_size;
+    cache->mpb_size = mc_amd->mpb_size;
+    microcode_patch->data = cache;
+
+    return microcode_patch;
+}
+
+static void free_patch(struct microcode_patch *microcode_patch)
+{
+    struct microcode_amd *mc_amd = microcode_patch->data;
+
+    xfree(mc_amd->equiv_cpu_table);
+    xfree(mc_amd->mpb);
+    xfree(mc_amd);
+    xfree(microcode_patch);
+}
+
+static enum microcode_match_result replace_patch(struct microcode_patch *new,
+                                                 struct microcode_patch *old)
+{
+    struct microcode_amd *new_mc = new->data;
+    struct microcode_header_amd *new_header = new_mc->mpb;
+    struct microcode_amd *old_mc = old->data;
+    struct microcode_header_amd *old_header = old_mc->mpb;
+
+    if ( new_header->processor_rev_id == old_header->processor_rev_id )
+    {
+        if ( new_header->patch_id <= old_header->patch_id )
+            return OLD_UCODE;
+
+        list_replace(&old->list, &new->list);
+        return NEW_UCODE;
+    }
+
+    return MIS_UCODE;
+}
+
 static int apply_microcode(unsigned int cpu)
 {
     unsigned long flags;
     struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu);
     uint32_t rev;
-    struct microcode_amd *mc_amd = uci->mc.mc_amd;
     struct microcode_header_amd *hdr;
+    struct microcode_patch *patch;
     int hw_err;
 
     /* We should bind the task to the CPU */
     BUG_ON(raw_smp_processor_id() != cpu);
 
-    if ( mc_amd == NULL )
+    patch = find_patch(cpu);
+    if ( patch == NULL )
         return -EINVAL;
 
-    hdr = mc_amd->mpb;
-    if ( hdr == NULL )
-        return -EINVAL;
+    hdr = patch->data;
+    BUG_ON(!hdr);
 
     spin_lock_irqsave(&microcode_update_lock, flags);
 
@@ -491,7 +557,20 @@ static int cpu_request_microcode(unsigned int cpu, const 
void *buf,
     while ( (error = get_ucode_from_buffer_amd(mc_amd, buf, bufsize,
                                                &offset)) == 0 )
     {
-        if ( microcode_fits(mc_amd, cpu) )
+        struct microcode_patch *microcode_patch = 
alloc_microcode_patch(mc_amd);
+
+        if ( IS_ERR(microcode_patch) )
+        {
+            error = PTR_ERR(microcode_patch);
+            break;
+        }
+
+        /*
+         * In order to support a system with mixed stepping CPUs, save
+         * this ucode patch before checking whether it matches with
+         * current CPU.
+         */
+        if ( save_patch(microcode_patch) && microcode_fits(mc_amd, cpu) )
         {
             error = apply_microcode(cpu);
             if ( error )
@@ -633,6 +712,9 @@ static const struct microcode_ops microcode_amd_ops = {
     .collect_cpu_info                 = collect_cpu_info,
     .apply_microcode                  = apply_microcode,
     .start_update                     = start_update,
+    .replace_patch                    = replace_patch,
+    .free_patch                       = free_patch,
+    .match_cpu                        = match_cpu,
 };
 
 int __init microcode_init_amd(void)
diff --git a/xen/arch/x86/microcode_intel.c b/xen/arch/x86/microcode_intel.c
index 1ed573a..fc35c8d 100644
--- a/xen/arch/x86/microcode_intel.c
+++ b/xen/arch/x86/microcode_intel.c
@@ -147,6 +147,15 @@ static enum microcode_match_result microcode_update_match(
     return MIS_UCODE;
 }
 
+static bool match_cpu(const struct microcode_patch *patch, unsigned int cpu)
+{
+    struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu);
+    int ret = microcode_update_match(patch->data, uci->cpu_sig.sig,
+                                     uci->cpu_sig.pf, uci->cpu_sig.rev);
+
+    return ret == NEW_UCODE;
+}
+
 static int microcode_sanity_check(void *mc)
 {
     struct microcode_header_intel *mc_header = mc;
@@ -237,6 +246,26 @@ static int microcode_sanity_check(void *mc)
     return 0;
 }
 
+static void free_patch(struct microcode_patch *patch)
+{
+    xfree(patch->data);
+    xfree(patch);
+}
+
+static enum microcode_match_result replace_patch(struct microcode_patch *new,
+                                                 struct microcode_patch *old)
+{
+    struct microcode_header_intel *old_header = old->data;
+    enum microcode_match_result ret =
+                microcode_update_match(new->data, old_header->sig,
+                                       old_header->pf, old_header->rev);
+
+    if ( ret == NEW_UCODE )
+        list_replace(&old->list, &new->list);
+
+    return ret;
+}
+
 /*
  * return 0 - no update found
  * return 1 - found update
@@ -248,6 +277,25 @@ static int get_matching_microcode(const void *mc, unsigned 
int cpu)
     const struct microcode_header_intel *mc_header = mc;
     unsigned long total_size = get_totalsize(mc_header);
     void *new_mc;
+    struct microcode_patch *microcode_patch = xmalloc(struct microcode_patch);
+    void *new_mc2 = xmalloc_bytes(total_size);
+
+    if ( !microcode_patch || !new_mc2 )
+    {
+        xfree(microcode_patch);
+        xfree(new_mc2);
+        printk(XENLOG_ERR "microcode: Can not allocate memory\n");
+        return -ENOMEM;
+    }
+    memcpy(new_mc2, mc, total_size);
+    microcode_patch->data = new_mc2;
+
+    /*
+     * In order to support a system with mixed stepping CPUs, save this ucode
+     * patch before checking whether it matches with current CPU.
+     */
+    if ( !save_patch(microcode_patch) )
+        return 0;
 
     if ( microcode_update_match(mc, uci->cpu_sig.sig, uci->cpu_sig.pf,
                                 uci->cpu_sig.rev) != NEW_UCODE )
@@ -276,18 +324,24 @@ static int apply_microcode(unsigned int cpu)
     unsigned int val[2];
     unsigned int cpu_num = raw_smp_processor_id();
     struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu_num);
+    struct microcode_intel *mc_intel;
+    struct microcode_patch *patch;
 
     /* We should bind the task to the CPU */
     BUG_ON(cpu_num != cpu);
 
-    if ( uci->mc.mc_intel == NULL )
+    patch = find_patch(cpu);
+    if ( !patch )
         return -EINVAL;
 
+    mc_intel = patch->data;
+    BUG_ON(!mc_intel);
+
     /* serialize access to the physical write to MSR 0x79 */
     spin_lock_irqsave(&microcode_update_lock, flags);
 
     /* write microcode via MSR 0x79 */
-    wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)uci->mc.mc_intel->bits);
+    wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)mc_intel->bits);
     wrmsrl(MSR_IA32_UCODE_REV, 0x0ULL);
 
     /* As documented in the SDM: Do a CPUID 1 here */
@@ -298,19 +352,19 @@ static int apply_microcode(unsigned int cpu)
     val[1] = (uint32_t)(msr_content >> 32);
 
     spin_unlock_irqrestore(&microcode_update_lock, flags);
-    if ( val[1] != uci->mc.mc_intel->hdr.rev )
+    if ( val[1] != mc_intel->hdr.rev )
     {
         printk(KERN_ERR "microcode: CPU%d update from revision "
                "%#x to %#x failed. Resulting revision is %#x.\n", cpu_num,
-               uci->cpu_sig.rev, uci->mc.mc_intel->hdr.rev, val[1]);
+               uci->cpu_sig.rev, mc_intel->hdr.rev, val[1]);
         return -EIO;
     }
     printk(KERN_INFO "microcode: CPU%d updated from revision "
            "%#x to %#x, date = %04x-%02x-%02x \n",
            cpu_num, uci->cpu_sig.rev, val[1],
-           uci->mc.mc_intel->hdr.date & 0xffff,
-           uci->mc.mc_intel->hdr.date >> 24,
-           (uci->mc.mc_intel->hdr.date >> 16) & 0xff);
+           mc_intel->hdr.date & 0xffff,
+           mc_intel->hdr.date >> 24,
+           (mc_intel->hdr.date >> 16) & 0xff);
     uci->cpu_sig.rev = val[1];
 
     return 0;
@@ -395,6 +449,9 @@ static const struct microcode_ops microcode_intel_ops = {
     .cpu_request_microcode            = cpu_request_microcode,
     .collect_cpu_info                 = collect_cpu_info,
     .apply_microcode                  = apply_microcode,
+    .replace_patch                    = replace_patch,
+    .free_patch                       = free_patch,
+    .match_cpu                        = match_cpu,
 };
 
 int __init microcode_init_intel(void)
diff --git a/xen/include/asm-x86/microcode.h b/xen/include/asm-x86/microcode.h
index 73ebe9a..fc98fed 100644
--- a/xen/include/asm-x86/microcode.h
+++ b/xen/include/asm-x86/microcode.h
@@ -1,6 +1,7 @@
 #ifndef ASM_X86__MICROCODE_H
 #define ASM_X86__MICROCODE_H
 
+#include <xen/list.h>
 #include <xen/percpu.h>
 
 enum microcode_match_result {
@@ -12,6 +13,11 @@ enum microcode_match_result {
 struct cpu_signature;
 struct ucode_cpu_info;
 
+struct microcode_patch {
+    struct list_head list;
+    void *data;
+};
+
 struct microcode_ops {
     int (*microcode_resume_match)(unsigned int cpu, const void *mc);
     int (*cpu_request_microcode)(unsigned int cpu, const void *buf,
@@ -19,6 +25,10 @@ struct microcode_ops {
     int (*collect_cpu_info)(unsigned int cpu, struct cpu_signature *csig);
     int (*apply_microcode)(unsigned int cpu);
     int (*start_update)(void);
+    enum microcode_match_result (*replace_patch)(struct microcode_patch *new,
+                                                 struct microcode_patch *old);
+    void (*free_patch)(struct microcode_patch *patch);
+    bool (*match_cpu)(const struct microcode_patch *patch, unsigned int cpu);
 };
 
 struct cpu_signature {
@@ -39,4 +49,7 @@ struct ucode_cpu_info {
 DECLARE_PER_CPU(struct ucode_cpu_info, ucode_cpu_info);
 extern const struct microcode_ops *microcode_ops;
 
+bool save_patch(struct microcode_patch *new_patch);
+struct microcode_patch *find_patch(unsigned int cpu);
+
 #endif /* ASM_X86__MICROCODE_H */
-- 
1.8.3.1


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