[PATCH v10 06/11] x86/time: add a domain context record for tsc_info...

[Paul Durrant <paul@xen.org>]

From: Paul Durrant <pdurrant@amazon.com>

... and update xen-domctx to dump some information describing the record.

NOTE: Whilst the record is x86 specific, it is visible directly in the common
      header as context record numbers should be unique across all
      architectures.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
Cc: Ian Jackson <iwj@xenproject.org>
Cc: Wei Liu <wl@xen.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <george.dunlap@citrix.com>
Cc: Julien Grall <julien@xen.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>

v10:
 - Re-base
 - Amend the specification now there is one
 - Kept Jan's R-b as the changes are cosmetic

v8:
 - Removed stray blank line

v7:
 - New in v7
---
 docs/specs/domain-context.md | 32 ++++++++++++++++++++++++++++++++
 tools/misc/xen-domctx.c      | 12 ++++++++++++
 xen/arch/x86/time.c          | 30 ++++++++++++++++++++++++++++++
 xen/include/public/save.h    |  8 ++++++++
 4 files changed, 82 insertions(+)

diff --git a/docs/specs/domain-context.md b/docs/specs/domain-context.md
index 95e9f9d1ab..8aa3466d96 100644
--- a/docs/specs/domain-context.md
+++ b/docs/specs/domain-context.md
@@ -155,6 +155,38 @@ The record body contains the following fields:
 | `buffer`    | The shared info (`length` being architecture    |
 |             | dependent[4])                                   |
 
+### TSC_INFO
+
+```
+    0       1       2       3       4       5       6       7    octet
++-------+-------+-------+-------+-------+-------+-------+-------+
+| type == 3                     | instance == 0                 |
++-------------------------------+-------------------------------+
+| length == 20                                                  |
++-------------------------------+-------------------------------+
+| mode                          | khz                           |
++-------------------------------+-------------------------------+
+| nsec                                                          |
++-------------------------------+-------------------------------+
+| incarnation                   |
++-------------------------------+
+```
+
+The record body contains the following fields:
+
+| Field         | Description                                   |
+|---------------|-----------------------------------------------|
+| `mode`        | 0x00000000: Default (emulate if necessary)    |
+|               | 0x00000001: Always emulate                    |
+|               | 0x00000002: Never emulate                     |
+|               |                                               |
+| `khz`         | The TSC frequency in kHz                      |
+|               |                                               |
+| `nsec`        | Elapsed time in nanoseconds                   |
+|               |                                               |
+| `incarnation` | Incarnation (counter indicating how many      |
+|               | times the TSC value has been set)             |
+
 * * *
 
 [1] See https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/designs/non-cooperative-migration.md
diff --git a/tools/misc/xen-domctx.c b/tools/misc/xen-domctx.c
index 5ea6de50d1..1a5dfb9d5a 100644
--- a/tools/misc/xen-domctx.c
+++ b/tools/misc/xen-domctx.c
@@ -136,6 +136,17 @@ static void dump_shared_info(void)
 #undef GET_FIELD_PTR
 }
 
+static void dump_tsc_info(void)
+{
+    struct domain_context_tsc_info *t;
+
+    GET_PTR(t);
+
+    printf("    TSC_INFO: mode: %u incarnation: %u\n"
+           "              khz %u nsec: %"PRIu64"\n",
+           t->mode, t->incarnation, t->khz, t->nsec);
+}
+
 static void dump_end(void)
 {
     struct domain_context_end *e;
@@ -225,6 +236,7 @@ int main(int argc, char **argv)
             {
             case DOMAIN_CONTEXT_START: dump_start(); break;
             case DOMAIN_CONTEXT_SHARED_INFO: dump_shared_info(); break;
+            case DOMAIN_CONTEXT_TSC_INFO: dump_tsc_info(); break;
             case DOMAIN_CONTEXT_END: dump_end(); break;
             default:
                 printf("Unknown type %u: skipping\n", rec->type);
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 8938c0f435..aec4bfb0f3 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -26,6 +26,7 @@
 #include <xen/symbols.h>
 #include <xen/keyhandler.h>
 #include <xen/guest_access.h>
+#include <xen/save.h>
 #include <asm/io.h>
 #include <asm/iocap.h>
 #include <asm/msr.h>
@@ -2451,6 +2452,35 @@ int tsc_set_info(struct domain *d,
     return 0;
 }
 
+static int save_tsc_info(struct domain *d, struct domain_ctxt_state *c,
+                         bool dry_run)
+{
+    struct domain_context_tsc_info t = {};
+
+    if ( !dry_run )
+        tsc_get_info(d, &t.mode, &t.nsec, &t.khz, &t.incarnation);
+
+    return domain_save_ctxt_rec(c, DOMAIN_CONTEXT_TSC_INFO, 0, &t, sizeof(t));
+}
+
+static int load_tsc_info(struct domain *d, struct domain_ctxt_state *c)
+{
+    struct domain_context_tsc_info t;
+    unsigned int i;
+    int rc;
+
+    rc = domain_load_ctxt_rec(c, DOMAIN_CONTEXT_TSC_INFO, &i, &t, sizeof(t));
+    if ( rc )
+        return rc;
+
+    if ( i ) /* expect only a single instance */
+        return -ENXIO;
+
+    return tsc_set_info(d, t.mode, t.nsec, t.khz, t.incarnation);
+}
+
+DOMAIN_REGISTER_CTXT_TYPE(TSC_INFO, save_tsc_info, load_tsc_info);
+
 /* vtsc may incur measurable performance degradation, diagnose with this */
 static void dump_softtsc(unsigned char key)
 {
diff --git a/xen/include/public/save.h b/xen/include/public/save.h
index bccbaadd0b..86881864cf 100644
--- a/xen/include/public/save.h
+++ b/xen/include/public/save.h
@@ -50,6 +50,7 @@ enum {
     DOMAIN_CONTEXT_END,
     DOMAIN_CONTEXT_START,
     DOMAIN_CONTEXT_SHARED_INFO,
+    DOMAIN_CONTEXT_TSC_INFO,
     /* New types go here */
     DOMAIN_CONTEXT_NR_TYPES
 };
@@ -69,6 +70,13 @@ struct domain_context_shared_info {
     uint8_t buffer[XEN_FLEX_ARRAY_DIM];
 };
 
+struct domain_context_tsc_info {
+    uint32_t mode;
+    uint32_t khz;
+    uint64_t nsec;
+    uint32_t incarnation;
+};
+
 /* Terminating entry */
 struct domain_context_end {};
 
-- 
2.20.1