Re: [Xen-devel] Can't boot as Xen dom0 due to commit fe055896

[Borislav Petkov <bp@xxxxxxx>]

On Fri, Dec 16, 2016 at 09:40:59AM -0500, Boris Ostrovsky wrote:
> It works

Thanks. Added your Tested-by.

> but I think both of the bugs we talked about yesterday still
> need to be fixed, they are not related to Xen.

For the one issue with the eq_id, I have the below cleanup for all the
args passing lined up for testing. For native_cpuid() you could send me
a patch. Unless you don't have time, then I can do it myself.

---
diff --git a/arch/x86/kernel/cpu/microcode/amd.c 
b/arch/x86/kernel/cpu/microcode/amd.c
index 6f353bdb3a25..122ed2249367 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -116,10 +116,11 @@ static inline u16 find_equiv_id(struct equiv_cpu_entry 
*equiv_cpu_table,
 
 /*
  * This scans the ucode blob for the proper container as we can have multiple
- * containers glued together.
+ * containers glued together. Returns the equivalence ID from the equivalence
+ * table.
  */
-static struct container
-find_proper_container(u8 *ucode, size_t size, u16 *ret_id)
+static u16
+find_proper_container(u8 *ucode, size_t size, struct container *ret_cont)
 {
        struct container ret = { NULL, 0 };
        u32 eax, ebx, ecx, edx;
@@ -138,7 +139,7 @@ find_proper_container(u8 *ucode, size_t size, u16 *ret_id)
        if (header[0] != UCODE_MAGIC ||
            header[1] != UCODE_EQUIV_CPU_TABLE_TYPE || /* type */
            header[2] == 0)                            /* size */
-               return ret;
+               return eq_id;
 
        eax = 0x00000001;
        ecx = 0;
@@ -163,8 +164,9 @@ find_proper_container(u8 *ucode, size_t size, u16 *ret_id)
                         * ucode update loop below
                         */
                        left = ret.size - offset;
-                       *ret_id = eq_id;
-                       return ret;
+
+                       *ret_cont = ret;
+                       return eq_id;
                }
 
                /*
@@ -189,7 +191,7 @@ find_proper_container(u8 *ucode, size_t size, u16 *ret_id)
                ucode     = data;
        }
 
-       return ret;
+       return eq_id;
 }
 
 static int __apply_microcode_amd(struct microcode_amd *mc_amd)
@@ -214,17 +216,18 @@ static int __apply_microcode_amd(struct microcode_amd 
*mc_amd)
  * and on 32-bit during save_microcode_in_initrd_amd() -- we can call
  * load_microcode_amd() to save equivalent cpu table and microcode patches in
  * kernel heap memory.
+ *
+ * Returns true if container found (sets @ret_cont), false otherwise.
  */
-static struct container
-apply_microcode_early_amd(void *ucode, size_t size, bool save_patch)
+static bool apply_microcode_early_amd(void *ucode, size_t size, bool 
save_patch,
+                                     struct container *ret_cont)
 {
-       struct container ret = { NULL, 0 };
        u8 (*patch)[PATCH_MAX_SIZE];
+       u32 rev, *header, *new_rev;
+       struct container ret;
        int offset, left;
-       u32 rev, *header;
-       u8  *data;
        u16 eq_id = 0;
-       u32 *new_rev;
+       u8  *data;
 
 #ifdef CONFIG_X86_32
        new_rev = (u32 *)__pa_nodebug(&ucode_new_rev);
@@ -235,11 +238,11 @@ apply_microcode_early_amd(void *ucode, size_t size, bool 
save_patch)
 #endif
 
        if (check_current_patch_level(&rev, true))
-               return (struct container){ NULL, 0 };
+               return false;
 
-       ret = find_proper_container(ucode, size, &eq_id);
+       eq_id = find_proper_container(ucode, size, &ret);
        if (!eq_id)
-               return (struct container){ NULL, 0 };
+               return false;
 
        this_equiv_id = eq_id;
        header = (u32 *)ret.data;
@@ -273,7 +276,11 @@ apply_microcode_early_amd(void *ucode, size_t size, bool 
save_patch)
                data   += offset;
                left   -= offset;
        }
-       return ret;
+
+       if (ret_cont)
+               *ret_cont = ret;
+
+       return true;
 }
 
 static bool get_builtin_microcode(struct cpio_data *cp, unsigned int family)
@@ -317,7 +324,7 @@ void __init load_ucode_amd_bsp(unsigned int family)
        /* Get BSP's CPUID.EAX(1), needed in load_microcode_amd() */
        uci->cpu_sig.sig = cpuid_eax(1);
 
-       apply_microcode_early_amd(cp.data, cp.size, true);
+       apply_microcode_early_amd(cp.data, cp.size, true, NULL);
 }
 
 #ifdef CONFIG_X86_32
@@ -349,7 +356,7 @@ void load_ucode_amd_ap(unsigned int family)
         * This would set amd_ucode_patch above so that the following APs can
         * use it directly instead of going down this path again.
         */
-       apply_microcode_early_amd(cp.data, cp.size, true);
+       apply_microcode_early_amd(cp.data, cp.size, true, NULL);
 }
 #else
 void load_ucode_amd_ap(unsigned int family)
@@ -387,8 +394,7 @@ void load_ucode_amd_ap(unsigned int family)
                        }
                }
 
-               cont = apply_microcode_early_amd(cp.data, cp.size, false);
-               if (!(cont.data && cont.size)) {
+               if (apply_microcode_early_amd(cp.data, cp.size, false, &cont)) {
                        cont.size = -1;
                        return;
                }
@@ -443,7 +449,7 @@ int __init save_microcode_in_initrd_amd(unsigned int fam)
                                return -EINVAL;
                        }
 
-                       cont = find_proper_container(cp.data, cp.size, &eq_id);
+                       eq_id = find_proper_container(cp.data, cp.size, &cont);
                        if (!eq_id) {
                                cont.size = -1;
                                return -EINVAL;

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 
(AG Nürnberg)
-- 

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