path: root/5ed69804-x86-ucode-fix-start-end-update.patch

# Commit 3659f54e9bd31f0f59268402fd67fb4b4118e184
# Date 2020-06-02 19:18:44 +0100
# Author Andrew Cooper <andrew.cooper3@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86/ucode: Fix errors with start/end_update()

c/s 9267a439c "x86/ucode: Document the behaviour of the microcode_ops hooks"
identified several poor behaviours of the start_update()/end_update_percpu()
hooks.

AMD have subsequently confirmed that OSVW don't, and are not expected to,
change across a microcode load, rendering all of this complexity unecessary.

Instead of fixing up the logic to not leave the OSVW state reset in a number
of corner cases, delete the logic entirely.

This in turn allows for the removal of the poorly-named 'start_update'
parameter to microcode_update_one(), and for svm_host_osvw_{init,reset}() to
become static.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/acpi/power.c
+++ b/xen/arch/x86/acpi/power.c
@@ -286,7 +286,7 @@ static int enter_state(u32 state)
     console_end_sync();
     watchdog_enable();
 
-    microcode_update_one(true);
+    microcode_update_one();
 
     if ( !recheck_cpu_features(0) )
         panic("Missing previously available feature(s)\n");
--- a/xen/arch/x86/microcode_amd.c
+++ b/xen/arch/x86/microcode_amd.c
@@ -24,7 +24,6 @@
 #include <asm/msr.h>
 #include <asm/processor.h>
 #include <asm/microcode.h>
-#include <asm/hvm/svm/svm.h>
 
 #define pr_debug(x...) ((void)0)
 
@@ -590,27 +589,10 @@ static struct microcode_patch *cpu_reque
     return patch;
 }
 
-#ifdef CONFIG_HVM
-static int start_update(void)
-{
-    /*
-     * svm_host_osvw_init() will be called on each cpu by calling '.end_update'
-     * in common code.
-     */
-    svm_host_osvw_reset();
-
-    return 0;
-}
-#endif
-
 static const struct microcode_ops microcode_amd_ops = {
     .cpu_request_microcode            = cpu_request_microcode,
     .collect_cpu_info                 = collect_cpu_info,
     .apply_microcode                  = apply_microcode,
-#ifdef CONFIG_HVM
-    .start_update                     = start_update,
-    .end_update_percpu                = svm_host_osvw_init,
-#endif
     .free_patch                       = free_patch,
     .compare_patch                    = compare_patch,
     .match_cpu                        = match_cpu,
--- a/xen/arch/x86/microcode.c
+++ b/xen/arch/x86/microcode.c
@@ -578,9 +578,6 @@ static int do_microcode_update(void *pat
     else
         ret = secondary_thread_fn();
 
-    if ( microcode_ops->end_update_percpu )
-        microcode_ops->end_update_percpu();
-
     return ret;
 }
 
@@ -652,16 +649,6 @@ static long microcode_update_helper(void
     }
     spin_unlock(&microcode_mutex);
 
-    if ( microcode_ops->start_update )
-    {
-        ret = microcode_ops->start_update();
-        if ( ret )
-        {
-            microcode_free_patch(patch);
-            goto put;
-        }
-    }
-
     cpumask_clear(&cpu_callin_map);
     atomic_set(&cpu_out, 0);
     atomic_set(&cpu_updated, 0);
@@ -760,28 +747,14 @@ static int __init microcode_init(void)
 __initcall(microcode_init);
 
 /* Load a cached update to current cpu */
-int microcode_update_one(bool start_update)
+int microcode_update_one(void)
 {
-    int err;
-
     if ( !microcode_ops )
         return -EOPNOTSUPP;
 
     microcode_ops->collect_cpu_info(&this_cpu(cpu_sig));
 
-    if ( start_update && microcode_ops->start_update )
-    {
-        err = microcode_ops->start_update();
-        if ( err )
-            return err;
-    }
-
-    err = microcode_update_cpu(NULL);
-
-    if ( microcode_ops->end_update_percpu )
-        microcode_ops->end_update_percpu();
-
-    return err;
+    return microcode_update_cpu(NULL);
 }
 
 /* BSP calls this function to parse ucode blob and then apply an update. */
@@ -825,7 +798,7 @@ int __init early_microcode_update_cpu(vo
     spin_unlock(&microcode_mutex);
     ASSERT(rc);
 
-    return microcode_update_one(true);
+    return microcode_update_one();
 }
 
 int __init early_microcode_init(void)
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1082,7 +1082,7 @@ static void svm_guest_osvw_init(struct d
     spin_unlock(&osvw_lock);
 }
 
-void svm_host_osvw_reset()
+static void svm_host_osvw_reset(void)
 {
     spin_lock(&osvw_lock);
 
@@ -1092,7 +1092,7 @@ void svm_host_osvw_reset()
     spin_unlock(&osvw_lock);
 }
 
-void svm_host_osvw_init()
+static void svm_host_osvw_init(void)
 {
     spin_lock(&osvw_lock);
 
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -358,7 +358,7 @@ void start_secondary(void *unused)
 
     initialize_cpu_data(cpu);
 
-    microcode_update_one(false);
+    microcode_update_one();
 
     /*
      * If MSR_SPEC_CTRL is available, apply Xen's default setting and discard
--- a/xen/include/asm-x86/hvm/svm/svm.h
+++ b/xen/include/asm-x86/hvm/svm/svm.h
@@ -93,9 +93,6 @@ extern u32 svm_feature_flags;
 #define DEFAULT_TSC_RATIO       0x0000000100000000ULL
 #define TSC_RATIO_RSVD_BITS     0xffffff0000000000ULL
 
-extern void svm_host_osvw_reset(void);
-extern void svm_host_osvw_init(void);
-
 /* EXITINFO1 fields on NPT faults */
 #define _NPT_PFEC_with_gla     32
 #define NPT_PFEC_with_gla      (1UL<<_NPT_PFEC_with_gla)
--- a/xen/include/asm-x86/microcode.h
+++ b/xen/include/asm-x86/microcode.h
@@ -24,8 +24,6 @@ struct microcode_ops {
                                                      size_t size);
     int (*collect_cpu_info)(struct cpu_signature *csig);
     int (*apply_microcode)(const struct microcode_patch *patch);
-    int (*start_update)(void);
-    void (*end_update_percpu)(void);
     void (*free_patch)(void *mc);
     bool (*match_cpu)(const struct microcode_patch *patch);
     enum microcode_match_result (*compare_patch)(
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -586,7 +586,7 @@ void microcode_set_module(unsigned int);
 int microcode_update(XEN_GUEST_HANDLE_PARAM(const_void), unsigned long len);
 int early_microcode_update_cpu(void);
 int early_microcode_init(void);
-int microcode_update_one(bool start_update);
+int microcode_update_one(void);
 int microcode_init_intel(void);
 int microcode_init_amd(void);