[xen staging] libs/guest: allow updating a cpu policy CPUID data

[patchbot@xxxxxxx]

commit 2d09c97e58ea455242a3862c16e732592841ddde
Author:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
AuthorDate: Wed Mar 17 16:49:55 2021 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue May 4 18:35:53 2021 +0100

    libs/guest: allow updating a cpu policy CPUID data
    
    Introduce a helper to update the CPUID policy using an array of
    xen_cpuid_leaf_t entries. Note the leaves present in the input
    xen_cpuid_leaf_t array will replace any existing leaves on the policy.
    
    No user of the interface introduced on this patch.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 tools/include/xenctrl.h         |  3 +++
 tools/libs/guest/xg_cpuid_x86.c | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h
index 27cec1b93f..543bd2a4c2 100644
--- a/tools/include/xenctrl.h
+++ b/tools/include/xenctrl.h
@@ -2608,6 +2608,9 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t 
domid,
 int xc_cpu_policy_serialise(xc_interface *xch, const xc_cpu_policy_t policy,
                             xen_cpuid_leaf_t *leaves, uint32_t *nr_leaves,
                             xen_msr_entry_t *msrs, uint32_t *nr_msrs);
+int xc_cpu_policy_update_cpuid(xc_interface *xch, xc_cpu_policy_t policy,
+                               const xen_cpuid_leaf_t *leaves,
+                               uint32_t nr);
 
 int xc_get_cpu_levelling_caps(xc_interface *xch, uint32_t *caps);
 int xc_get_cpu_featureset(xc_interface *xch, uint32_t index,
diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
index 0c9b3a960f..713649edde 100644
--- a/tools/libs/guest/xg_cpuid_x86.c
+++ b/tools/libs/guest/xg_cpuid_x86.c
@@ -822,3 +822,23 @@ int xc_cpu_policy_serialise(xc_interface *xch, const 
xc_cpu_policy_t p,
     errno = 0;
     return 0;
 }
+
+int xc_cpu_policy_update_cpuid(xc_interface *xch, xc_cpu_policy_t policy,
+                               const xen_cpuid_leaf_t *leaves,
+                               uint32_t nr)
+{
+    unsigned int err_leaf = -1, err_subleaf = -1;
+    int rc = x86_cpuid_copy_from_buffer(&policy->cpuid, leaves, nr,
+                                        &err_leaf, &err_subleaf);
+
+    if ( rc )
+    {
+        if ( err_leaf != -1 )
+            ERROR("Failed to update CPUID (err leaf %#x, subleaf %#x) (%d = 
%s)",
+                  err_leaf, err_subleaf, -rc, strerror(-rc));
+        errno = -rc;
+        rc = -1;
+    }
+
+    return rc;
+}
--
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