[PATCH v3 2/5] x86: Refactor microcode_update() hypercall with flags

[Fouad Hilly <fouad.hilly@xxxxxxxxx>]

Refactor microcode_update() by adding a flags field.
struct xenpf_microcode_update2 added with uint32_t flags field.
Introduce XENPF_microcode_update2 hypercall to handle flags field.
Introduce ucode_force_flag to microcode_update_helper.

Signed-off-by: Fouad Hilly <fouad.hilly@xxxxxxxxx>
---
[v3]
1- Updated Commit message description.
2- Revereted changes to a stable ABI and introduced a new struct.
3- ucode_force_flag updated from static to a local variable.
4- microcode_update() updated to reject unsupported flags yet.

[v2]
1- Update message description to highlight interface change.
2- Removed extra empty lines.
3- removed unnecessary define.
4- Corrected long lines.
5- Removed ternary operator.
6- Introduced static ucode_update_flags, which will be used later to determine 
local ucode_force_flag.
 xen/arch/x86/cpu/microcode/core.c    | 15 ++++++++++++---
 xen/arch/x86/include/asm/microcode.h |  3 ++-
 xen/arch/x86/platform_hypercall.c    | 12 +++++++++++-
 xen/include/public/platform.h        | 14 ++++++++++++++
 4 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/cpu/microcode/core.c 
b/xen/arch/x86/cpu/microcode/core.c
index e738a88f5cd1..4a18ddd2683b 100644
--- a/xen/arch/x86/cpu/microcode/core.c
+++ b/xen/arch/x86/cpu/microcode/core.c
@@ -40,6 +40,8 @@
 #include <asm/processor.h>
 #include <asm/setup.h>
 
+#include <public/platform.h>
+
 #include "private.h"
 
 /*
@@ -570,6 +572,7 @@ static int cf_check do_microcode_update(void *patch)
 }
 
 struct ucode_buf {
+    unsigned int flags;
     unsigned int len;
     char buffer[];
 };
@@ -580,6 +583,7 @@ static long cf_check microcode_update_helper(void *data)
     struct ucode_buf *buffer = data;
     unsigned int cpu, updated;
     struct microcode_patch *patch;
+    bool ucode_force_flag = buffer->flags == XENPF_UCODE_FLAG_FORCE_SET;
 
     /* cpu_online_map must not change during update */
     if ( !get_cpu_maps() )
@@ -633,12 +637,12 @@ static long cf_check microcode_update_helper(void *data)
                                   microcode_cache);
 
         if ( result != NEW_UCODE &&
-             !(opt_ucode_allow_same && result == SAME_UCODE) )
+             !((opt_ucode_allow_same || ucode_force_flag) && result == 
SAME_UCODE) )
         {
             spin_unlock(&microcode_mutex);
             printk(XENLOG_WARNING
                    "microcode: couldn't find any newer%s revision in the 
provided blob!\n",
-                   opt_ucode_allow_same ? " (or the same)" : "");
+                   (opt_ucode_allow_same || ucode_force_flag) ? " (or the 
same)" : "");
             microcode_free_patch(patch);
             ret = -ENOENT;
 
@@ -708,11 +712,15 @@ static long cf_check microcode_update_helper(void *data)
     return ret;
 }
 
-int microcode_update(XEN_GUEST_HANDLE(const_void) buf, unsigned long len)
+int microcode_update(XEN_GUEST_HANDLE(const_void) buf,
+                     unsigned long len, unsigned int flags)
 {
     int ret;
     struct ucode_buf *buffer;
 
+    if ( flags > 1 )
+        return -EINVAL;
+
     if ( len != (uint32_t)len )
         return -E2BIG;
 
@@ -730,6 +738,7 @@ int microcode_update(XEN_GUEST_HANDLE(const_void) buf, 
unsigned long len)
         return -EFAULT;
     }
     buffer->len = len;
+    buffer->flags = flags;
 
     /*
      * Always queue microcode_update_helper() on CPU0.  Most of the logic
diff --git a/xen/arch/x86/include/asm/microcode.h 
b/xen/arch/x86/include/asm/microcode.h
index 8f59b20b0289..57c08205d475 100644
--- a/xen/arch/x86/include/asm/microcode.h
+++ b/xen/arch/x86/include/asm/microcode.h
@@ -22,7 +22,8 @@ struct cpu_signature {
 DECLARE_PER_CPU(struct cpu_signature, cpu_sig);
 
 void microcode_set_module(unsigned int idx);
-int microcode_update(XEN_GUEST_HANDLE(const_void) buf, unsigned long len);
+int microcode_update(XEN_GUEST_HANDLE(const_void) buf,
+                     unsigned long len, unsigned int flags);
 int early_microcode_init(unsigned long *module_map,
                          const struct multiboot_info *mbi);
 int microcode_init_cache(unsigned long *module_map,
diff --git a/xen/arch/x86/platform_hypercall.c 
b/xen/arch/x86/platform_hypercall.c
index 95467b88ab64..a22f2929896e 100644
--- a/xen/arch/x86/platform_hypercall.c
+++ b/xen/arch/x86/platform_hypercall.c
@@ -311,7 +311,17 @@ ret_t do_platform_op(
 
         guest_from_compat_handle(data, op->u.microcode.data);
 
-        ret = microcode_update(data, op->u.microcode.length);
+        ret = microcode_update(data, op->u.microcode.length, 0);
+        break;
+    }
+
+    case XENPF_microcode_update2:
+    {
+        XEN_GUEST_HANDLE(const_void) data;
+
+        guest_from_compat_handle(data, op->u.microcode2.data);
+
+        ret = microcode_update(data, op->u.microcode2.length, 
op->u.microcode2.flags);
         break;
     }
 
diff --git a/xen/include/public/platform.h b/xen/include/public/platform.h
index 15777b541690..a30de7153779 100644
--- a/xen/include/public/platform.h
+++ b/xen/include/public/platform.h
@@ -624,6 +624,19 @@ struct xenpf_ucode_revision {
 typedef struct xenpf_ucode_revision xenpf_ucode_revision_t;
 DEFINE_XEN_GUEST_HANDLE(xenpf_ucode_revision_t);
 
+/* Hypercall to microcode_update with flags */
+#define XENPF_microcode_update2    66
+struct xenpf_microcode_update2 {
+    /* IN variables. */
+    uint32_t flags;                   /* Flags to be passed with ucode. */
+/* Force to skip microcode version check when set */
+#define XENPF_UCODE_FLAG_FORCE_SET     1
+    uint32_t length;                  /* Length of microcode data. */
+    XEN_GUEST_HANDLE(const_void) data;/* Pointer to microcode data */
+};
+typedef struct xenpf_microcode_update2 xenpf_microcode_update2_t;
+DEFINE_XEN_GUEST_HANDLE(xenpf_microcode_update2_t);
+
 /*
  * ` enum neg_errnoval
  * ` HYPERVISOR_platform_op(const struct xen_platform_op*);
@@ -656,6 +669,7 @@ struct xen_platform_op {
         xenpf_symdata_t               symdata;
         xenpf_dom0_console_t          dom0_console;
         xenpf_ucode_revision_t        ucode_revision;
+        xenpf_microcode_update2_t     microcode2;
         uint8_t                       pad[128];
     } u;
 };
-- 
2.42.0