x86: Merge a domain's {cpuid,msr} policy objects

Right now, they're the same underlying type, containing disjoint information.

Drop the d->arch.msr pointer, and union d->arch.cpuid to give it a second name
of cpu_policy in the interim.

Merge init_domain_{cpuid,msr}_policy() into a single init_domain_cpu_policy(),
moving the implementation into cpu-policy.c

No practical change.  This undoes the transient doubling of storage space from
earlier patches.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit bd13dae348)

xen/arch/x86/cpu-policy.c

@@ -1,10 +1,13 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 #include <xen/cache.h>
 #include <xen/kernel.h>
+#include <xen/sched.h>
 
 #include <xen/lib/x86/cpu-policy.h>
 
 #include <asm/cpu-policy.h>
+#include <asm/msr-index.h>
+#include <asm/setup.h>
 
 struct cpu_policy __read_mostly       raw_cpu_policy;
 struct cpu_policy __read_mostly      host_cpu_policy;
@@ -16,3 +19,49 @@ struct cpu_policy __read_mostly    pv_def_cpu_policy;
 struct cpu_policy __read_mostly   hvm_max_cpu_policy;
 struct cpu_policy __read_mostly   hvm_def_cpu_policy;
 #endif
+
+int init_domain_cpu_policy(struct domain *d)
+{
+    struct cpu_policy *p = is_pv_domain(d)
+        ? (IS_ENABLED(CONFIG_PV)  ?  &pv_def_cpu_policy : NULL)
+        : (IS_ENABLED(CONFIG_HVM) ? &hvm_def_cpu_policy : NULL);
+
+    if ( !p )
+    {
+        ASSERT_UNREACHABLE();
+        return -EOPNOTSUPP;
+    }
+
+    p = xmemdup(p);
+    if ( !p )
+        return -ENOMEM;
+
+    /* See comment in ctxt_switch_levelling() */
+    if ( !opt_dom0_cpuid_faulting && is_control_domain(d) && is_pv_domain(d) )
+        p->platform_info.cpuid_faulting = false;
+
+    /*
+     * Expose the "hardware speculation behaviour" bits of ARCH_CAPS to dom0,
+     * so dom0 can turn off workarounds as appropriate.  Temporary, until the
+     * domain policy logic gains a better understanding of MSRs.
+     */
+    if ( is_hardware_domain(d) && cpu_has_arch_caps )
+    {
+        uint64_t val;
+
+        rdmsrl(MSR_ARCH_CAPABILITIES, val);
+
+        p->arch_caps.raw = val &
+            (ARCH_CAPS_RDCL_NO | ARCH_CAPS_IBRS_ALL | ARCH_CAPS_RSBA |
+             ARCH_CAPS_SSB_NO | ARCH_CAPS_MDS_NO | ARCH_CAPS_IF_PSCHANGE_MC_NO |
+             ARCH_CAPS_TAA_NO | ARCH_CAPS_SBDR_SSDP_NO | ARCH_CAPS_FBSDP_NO |
+             ARCH_CAPS_PSDP_NO | ARCH_CAPS_FB_CLEAR | ARCH_CAPS_RRSBA |
+             ARCH_CAPS_BHI_NO | ARCH_CAPS_PBRSB_NO);
+    }
+
+    d->arch.cpu_policy = p;
+
+    recalculate_cpuid_policy(d);
+
+    return 0;
+}

xen/arch/x86/cpuid.c

@@ -755,29 +755,6 @@ void recalculate_cpuid_policy(struct domain *d)
         p->extd.raw[0x19] = EMPTY_LEAF;
 }
 
-int init_domain_cpuid_policy(struct domain *d)
-{
-    struct cpuid_policy *p = is_pv_domain(d)
-        ? (IS_ENABLED(CONFIG_PV)  ?  &pv_def_cpu_policy : NULL)
-        : (IS_ENABLED(CONFIG_HVM) ? &hvm_def_cpu_policy : NULL);
-
-    if ( !p )
-    {
-        ASSERT_UNREACHABLE();
-        return -EOPNOTSUPP;
-    }
-
-    p = xmemdup(p);
-    if ( !p )
-        return -ENOMEM;
-
-    d->arch.cpuid = p;
-
-    recalculate_cpuid_policy(d);
-
-    return 0;
-}
-
 void __init init_dom0_cpuid_policy(struct domain *d)
 {
     struct cpuid_policy *p = d->arch.cpuid;

xen/arch/x86/domain.c

@@ -64,6 +64,7 @@
 #include <xen/numa.h>
 #include <xen/iommu.h>
 #include <compat/vcpu.h>
+#include <asm/cpu-policy.h>
 #include <asm/psr.h>
 #include <asm/pv/domain.h>
 #include <asm/pv/mm.h>
@@ -534,8 +535,7 @@ int arch_domain_create(struct domain *d,
 
         d->arch.ctxt_switch = &idle_csw;
 
-        d->arch.cpuid = ZERO_BLOCK_PTR; /* Catch stray misuses. */
-        d->arch.msr = ZERO_BLOCK_PTR;
+        d->arch.cpu_policy = ZERO_BLOCK_PTR; /* Catch stray misuses. */
 
         return 0;
     }
@@ -588,10 +588,7 @@ int arch_domain_create(struct domain *d,
         goto fail;
     paging_initialised = true;
 
-    if ( (rc = init_domain_cpuid_policy(d)) )
-        goto fail;
-
-    if ( (rc = init_domain_msr_policy(d)) )
+    if ( (rc = init_domain_cpu_policy(d)) )
         goto fail;
 
     d->arch.ioport_caps =
@@ -660,8 +657,7 @@ int arch_domain_create(struct domain *d,
     iommu_domain_destroy(d);
     cleanup_domain_irq_mapping(d);
     free_xenheap_page(d->shared_info);
-    xfree(d->arch.cpuid);
-    xfree(d->arch.msr);
+    XFREE(d->arch.cpu_policy);
     if ( paging_initialised )
         paging_final_teardown(d);
     free_perdomain_mappings(d);
@@ -675,8 +671,7 @@ void arch_domain_destroy(struct domain *d)
         hvm_domain_destroy(d);
 
     xfree(d->arch.e820);
-    xfree(d->arch.cpuid);
-    xfree(d->arch.msr);
+    XFREE(d->arch.cpu_policy);
 
     free_domain_pirqs(d);
     if ( !is_idle_domain(d) )

xen/arch/x86/domctl.c

@@ -219,11 +219,11 @@ void domain_cpu_policy_changed(struct domain *d)
 static int update_domain_cpu_policy(struct domain *d,
                                     xen_domctl_cpu_policy_t *xdpc)
 {
-    struct old_cpu_policy new = {};
+    struct cpu_policy *new;
     struct cpu_policy *sys = is_pv_domain(d)
         ? (IS_ENABLED(CONFIG_PV)  ?  &pv_max_cpu_policy : NULL)
         : (IS_ENABLED(CONFIG_HVM) ? &hvm_max_cpu_policy : NULL);
-    struct old_cpu_policy old_sys = { sys, sys };
+    struct old_cpu_policy old_sys = { sys, sys }, old_new;
     struct cpu_policy_errors err = INIT_CPU_POLICY_ERRORS;
     int ret = -ENOMEM;
 
@@ -233,33 +233,33 @@ static int update_domain_cpu_policy(struct domain *d,
         return -EOPNOTSUPP;
     }
 
-    /* Start by copying the domain's existing policies. */
-    if ( !(new.cpuid = xmemdup(d->arch.cpuid)) ||
-         !(new.msr   = xmemdup(d->arch.msr)) )
+    /* Start by copying the domain's existing policy. */
+    if ( !(new = xmemdup(d->arch.cpu_policy)) )
         goto out;
 
+    old_new = (struct old_cpu_policy){ new, new };
+
     /* Merge the toolstack provided data. */
     if ( (ret = x86_cpuid_copy_from_buffer(
-              new.cpuid, xdpc->leaves, xdpc->nr_leaves,
+              new, xdpc->leaves, xdpc->nr_leaves,
               &err.leaf, &err.subleaf)) ||
          (ret = x86_msr_copy_from_buffer(
-              new.msr, xdpc->msrs, xdpc->nr_msrs, &err.msr)) )
+              new, xdpc->msrs, xdpc->nr_msrs, &err.msr)) )
         goto out;
 
     /* Trim any newly-stale out-of-range leaves. */
-    x86_cpuid_policy_clear_out_of_range_leaves(new.cpuid);
+    x86_cpuid_policy_clear_out_of_range_leaves(new);
 
     /* Audit the combined dataset. */
-    ret = x86_cpu_policies_are_compatible(&old_sys, &new, &err);
+    ret = x86_cpu_policies_are_compatible(&old_sys, &old_new, &err);
     if ( ret )
         goto out;
 
     /*
-     * Audit was successful.  Replace existing policies, leaving the old
-     * policies to be freed.
+     * Audit was successful.  Replace the existing policy, leaving the old one
+     * to be freed.
      */
-    SWAP(new.cpuid, d->arch.cpuid);
-    SWAP(new.msr,   d->arch.msr);
+    SWAP(new, d->arch.cpu_policy);
 
     /* TODO: Drop when x86_cpu_policies_are_compatible() is completed. */
     recalculate_cpuid_policy(d);
@@ -268,9 +268,8 @@ static int update_domain_cpu_policy(struct domain *d,
     domain_cpu_policy_changed(d);
 
  out:
-    /* Free whichever cpuid/msr structs are not installed in struct domain. */
-    xfree(new.cpuid);
-    xfree(new.msr);
+    /* Free whichever struct is not installed in struct domain. */
+    xfree(new);
 
     if ( ret )
     {
@@ -1461,7 +1460,7 @@ long arch_do_domctl(
         if ( guest_handle_is_null(domctl->u.cpu_policy.leaves) )
             domctl->u.cpu_policy.nr_leaves = CPUID_MAX_SERIALISED_LEAVES;
         else if ( (ret = x86_cpuid_copy_to_buffer(
-                       d->arch.cpuid,
+                       d->arch.cpu_policy,
                        domctl->u.cpu_policy.leaves,
                        &domctl->u.cpu_policy.nr_leaves)) )
             break;
@@ -1470,7 +1469,7 @@ long arch_do_domctl(
         if ( guest_handle_is_null(domctl->u.cpu_policy.msrs) )
             domctl->u.cpu_policy.nr_msrs = MSR_MAX_SERIALISED_ENTRIES;
         else if ( (ret = x86_msr_copy_to_buffer(
-                       d->arch.msr,
+                       d->arch.cpu_policy,
                        domctl->u.cpu_policy.msrs,
                        &domctl->u.cpu_policy.nr_msrs)) )
             break;

xen/arch/x86/msr.c

@@ -119,50 +119,6 @@ void __init init_guest_msr_policy(void)
     }
 }
 
-int init_domain_msr_policy(struct domain *d)
-{
-    struct msr_policy *mp = is_pv_domain(d)
-        ? (IS_ENABLED(CONFIG_PV)  ?  &pv_def_cpu_policy : NULL)
-        : (IS_ENABLED(CONFIG_HVM) ? &hvm_def_cpu_policy : NULL);
-
-    if ( !mp )
-    {
-        ASSERT_UNREACHABLE();
-        return -EOPNOTSUPP;
-    }
-
-    mp = xmemdup(mp);
-    if ( !mp )
-        return -ENOMEM;
-
-    /* See comment in ctxt_switch_levelling() */
-    if ( !opt_dom0_cpuid_faulting && is_control_domain(d) && is_pv_domain(d) )
-        mp->platform_info.cpuid_faulting = false;
-
-    /*
-     * Expose the "hardware speculation behaviour" bits of ARCH_CAPS to dom0,
-     * so dom0 can turn off workarounds as appropriate.  Temporary, until the
-     * domain policy logic gains a better understanding of MSRs.
-     */
-    if ( is_hardware_domain(d) && cpu_has_arch_caps )
-    {
-        uint64_t val;
-
-        rdmsrl(MSR_ARCH_CAPABILITIES, val);
-
-        mp->arch_caps.raw = val &
-            (ARCH_CAPS_RDCL_NO | ARCH_CAPS_IBRS_ALL | ARCH_CAPS_RSBA |
-             ARCH_CAPS_SSB_NO | ARCH_CAPS_MDS_NO | ARCH_CAPS_IF_PSCHANGE_MC_NO |
-             ARCH_CAPS_TAA_NO | ARCH_CAPS_SBDR_SSDP_NO | ARCH_CAPS_FBSDP_NO |
-             ARCH_CAPS_PSDP_NO | ARCH_CAPS_FB_CLEAR | ARCH_CAPS_RRSBA |
-             ARCH_CAPS_BHI_NO | ARCH_CAPS_PBRSB_NO);
-    }
-
-    d->arch.msr = mp;
-
-    return 0;
-}
-
 int init_vcpu_msr_policy(struct vcpu *v)
 {
     struct vcpu_msrs *msrs = xzalloc(struct vcpu_msrs);

xen/include/asm-x86/cpu-policy.h

@@ -3,6 +3,7 @@
 #define X86_CPU_POLICY_H
 
 struct cpu_policy;
+struct domain;
 
 extern struct cpu_policy     raw_cpu_policy;
 extern struct cpu_policy    host_cpu_policy;
@@ -11,4 +12,7 @@ extern struct cpu_policy  pv_def_cpu_policy;
 extern struct cpu_policy hvm_max_cpu_policy;
 extern struct cpu_policy hvm_def_cpu_policy;
 
+/* Allocate and initialise a CPU policy suitable for the domain. */
+int init_domain_cpu_policy(struct domain *d);
+
 #endif /* X86_CPU_POLICY_H */

xen/include/asm-x86/cpuid.h

@@ -49,9 +49,6 @@ extern struct cpuidmasks cpuidmask_defaults;
 /* Check that all previously present features are still available. */
 bool recheck_cpu_features(unsigned int cpu);
 
-/* Allocate and initialise a CPUID policy suitable for the domain. */
-int init_domain_cpuid_policy(struct domain *d);
-
 /* Apply dom0-specific tweaks to the CPUID policy. */
 void init_dom0_cpuid_policy(struct domain *d);
 

xen/include/asm-x86/domain.h

@@ -368,9 +368,16 @@ struct arch_domain
      */
     uint8_t x87_fip_width;
 
-    /* CPUID and MSR policy objects. */
-    struct cpuid_policy *cpuid;
-    struct msr_policy *msr;
+    /*
+     * The domain's CPU Policy.  "cpu_policy" is considered the canonical
+     * pointer, but the "cpuid" and "msr" aliases exist so the most
+     * appropriate one can be used for local code clarity.
+     */
+    union {
+        struct cpu_policy *cpu_policy;
+        struct cpu_policy *cpuid;
+        struct cpu_policy *msr;
+    };
 
     struct PITState vpit;
 

xen/include/asm-x86/msr.h

@@ -334,7 +334,6 @@ struct vcpu_msrs
 };
 
 void init_guest_msr_policy(void);
-int init_domain_msr_policy(struct domain *d);
 int init_vcpu_msr_policy(struct vcpu *v);
 
 /*