@@ -817,6 +817,10 @@ int xc_cpu_policy_get_msr(xc_interface *xch, const xc_cpu_policy_t *policy,
bool xc_cpu_policy_is_compatible(xc_interface *xch, xc_cpu_policy_t *host,
xc_cpu_policy_t *guest);
+/* Make a policy compatible with pre-4.13 Xen versions. */
+void xc_cpu_policy_make_compat_4_12(xc_interface *xch, xc_cpu_policy_t *policy,
+ const xc_cpu_policy_t *host, bool hvm);
+
int xc_get_cpu_levelling_caps(xc_interface *xch, uint32_t *caps);
int xc_get_cpu_featureset(xc_interface *xch, uint32_t index,
uint32_t *nr_features, uint32_t *featureset);
@@ -432,6 +432,8 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
unsigned int i, nr_leaves, nr_msrs;
xen_cpuid_leaf_t *leaves = NULL;
struct cpuid_policy *p = NULL;
+ xc_cpu_policy_t *policy = NULL;
+ xc_cpu_policy_t *host = NULL;
uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
uint32_t host_featureset[FEATURESET_NR_ENTRIES] = {};
uint32_t len = ARRAY_SIZE(host_featureset);
@@ -454,7 +456,9 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
rc = -ENOMEM;
if ( (leaves = calloc(nr_leaves, sizeof(*leaves))) == NULL ||
- (p = calloc(1, sizeof(*p))) == NULL )
+ (p = calloc(1, sizeof(*p))) == NULL ||
+ (policy = xc_cpu_policy_init()) == NULL ||
+ (host = xc_cpu_policy_init()) == NULL )
goto out;
/* Get the host policy. */
@@ -473,6 +477,8 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
}
}
+ cpuid_featureset_to_policy(host_featureset, &host->cpuid);
+
/* Get the domain's default policy. */
nr_msrs = 0;
rc = get_system_cpu_policy(xch, di.hvm ? XEN_SYSCTL_cpu_policy_hvm_default
@@ -496,23 +502,9 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
if ( restore )
{
- /*
- * Account for feature which have been disabled by default since Xen 4.13,
- * so migrated-in VM's don't risk seeing features disappearing.
- */
- p->basic.rdrand = test_bit(X86_FEATURE_RDRAND, host_featureset);
- p->feat.hle = test_bit(X86_FEATURE_HLE, host_featureset);
- p->feat.rtm = test_bit(X86_FEATURE_RTM, host_featureset);
-
- if ( di.hvm )
- {
- p->feat.mpx = test_bit(X86_FEATURE_MPX, host_featureset);
- }
-
- /* Clamp maximum leaves to the ones supported on 4.12. */
- p->basic.max_leaf = min(p->basic.max_leaf, 0xdu);
- p->feat.max_subleaf = 0;
- p->extd.max_leaf = min(p->extd.max_leaf, 0x8000001c);
+ policy->cpuid = *p;
+ xc_cpu_policy_make_compat_4_12(xch, policy, host, di.hvm);
+ *p = policy->cpuid;
}
if ( featureset )
@@ -662,6 +654,8 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
out:
free(p);
free(leaves);
+ xc_cpu_policy_destroy(policy);
+ xc_cpu_policy_destroy(host);
return rc;
}
@@ -919,3 +913,23 @@ bool xc_cpu_policy_is_compatible(xc_interface *xch, xc_cpu_policy_t *host,
return false;
}
+
+void xc_cpu_policy_make_compat_4_12(xc_interface *xch, xc_cpu_policy_t *policy,
+ const xc_cpu_policy_t *host, bool hvm)
+{
+ /*
+ * Account for features which have been disabled by default since Xen 4.13,
+ * so migrated-in VM's don't risk seeing features disappearing.
+ */
+ policy->cpuid.basic.rdrand = host->cpuid.basic.rdrand;
+ policy->cpuid.feat.hle = host->cpuid.feat.hle;
+ policy->cpuid.feat.rtm = host->cpuid.feat.rtm;
+
+ if ( hvm )
+ policy->cpuid.feat.mpx = host->cpuid.feat.mpx;
+
+ /* Clamp maximum leaves to the ones supported on pre-4.13. */
+ policy->cpuid.basic.max_leaf = min(policy->cpuid.basic.max_leaf, 0xdu);
+ policy->cpuid.feat.max_subleaf = 0;
+ policy->cpuid.extd.max_leaf = min(policy->cpuid.extd.max_leaf, 0x8000001c);
+}
Older Xen versions used to expose some CPUID bits which are no longer exposed by default. In order to keep a compatible behavior with guests migrated from versions of Xen that don't encode the CPUID data on the migration stream introduce a function that sets the same bits as older Xen versions. This is pulled out from xc_cpuid_apply_policy which already has this logic present. No functional change intended. Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> --- Changes since v6: - Pass the host policy to the newly created helper. Changes since v3: - Rename function to xc_cpu_policy_make_compat_4_12. Changes since v1: - Move comments and explicitly mention pre-4.13 Xen. --- tools/include/xenguest.h | 4 +++ tools/libs/guest/xg_cpuid_x86.c | 50 +++++++++++++++++++++------------ 2 files changed, 36 insertions(+), 18 deletions(-)