[Xen-devel] [PATCH v2 1/2] x86/cpuid: Drop a guests cached x86 family and model information

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The model information isn't used at all, and the family information is only
used once.

Make get_cpu_family() a static inline (as it is just basic calculation, and
the function call is probably more expensive than the function itself) and
rearange the logic to avoid calculating model entirely if the caller doesn't
want it.

Calculate a guests family only when necessary in hvm_select_ioreq_server().

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Paul Durrant <paul.durrant@xxxxxxxxxx>

v2: Broken out from previous v1
---
 xen/arch/x86/cpu/common.c       | 19 -------------------
 xen/arch/x86/domain.c           |  2 --
 xen/arch/x86/domctl.c           |  2 --
 xen/arch/x86/hvm/ioreq.c        |  6 ++++--
 xen/include/asm-x86/cpuid.h     |  2 +-
 xen/include/asm-x86/domain.h    |  2 --
 xen/include/asm-x86/processor.h | 23 ++++++++++++++++++++++-
 7 files changed, 27 insertions(+), 29 deletions(-)

diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index 7d6d024..56a2331 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -186,25 +186,6 @@ int get_cpu_vendor(uint32_t b, uint32_t c, uint32_t d, 
enum get_cpu_vendor mode)
        return X86_VENDOR_UNKNOWN;
 }
 
-uint8_t get_cpu_family(uint32_t raw, uint8_t *model, uint8_t *stepping)
-{
-       uint8_t fam, mod;
-
-       fam = (raw >> 8) & 0xf;
-       if (fam == 0xf)
-               fam += (raw >> 20) & 0xff;
-
-       mod = (raw >> 4) & 0xf;
-       if (fam >= 0x6)
-               mod |= (raw >> 12) & 0xf0;
-
-       if (model)
-               *model = mod;
-       if (stepping)
-               *stepping = raw & 0xf;
-       return fam;
-}
-
 static inline u32 _phys_pkg_id(u32 cpuid_apic, int index_msb)
 {
        return cpuid_apic >> index_msb;
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 369a83a..f966da7 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -607,8 +607,6 @@ int arch_domain_create(struct domain *d, unsigned int 
domcr_flags,
             goto fail;
 
         d->arch.x86_vendor = boot_cpu_data.x86_vendor;
-        d->arch.x86        = boot_cpu_data.x86;
-        d->arch.x86_model  = boot_cpu_data.x86_model;
 
         d->arch.ioport_caps = 
             rangeset_new(d, "I/O Ports", RANGESETF_prettyprint_hex);
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 772c5d2..0458d8f 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -171,8 +171,6 @@ static int update_domain_cpuid_info(struct domain *d,
     }
 
     case 1:
-        d->arch.x86 = get_cpu_family(ctl->eax, &d->arch.x86_model, NULL);
-
         if ( is_pv_domain(d) && ((levelling_caps & LCAP_1cd) == LCAP_1cd) )
         {
             uint64_t mask = cpuidmask_defaults._1cd;
diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index 2830f6c..8ad8465 100644
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -1125,7 +1125,7 @@ struct hvm_ioreq_server *hvm_select_ioreq_server(struct 
domain *d,
          (p->addr & ~3) == 0xcfc &&
          CF8_ENABLED(cf8) )
     {
-        uint32_t sbdf;
+        uint32_t sbdf, x86_fam;
 
         /* PCI config data cycle */
 
@@ -1141,7 +1141,9 @@ struct hvm_ioreq_server *hvm_select_ioreq_server(struct 
domain *d,
         /* AMD extended configuration space access? */
         if ( CF8_ADDR_HI(cf8) &&
              d->arch.x86_vendor == X86_VENDOR_AMD &&
-             d->arch.x86 >= 0x10 && d->arch.x86 <= 0x17 )
+             (x86_fam = get_cpu_family(
+                 d->arch.cpuid->basic.raw_fms, NULL, NULL)) > 0x10 &&
+             x86_fam <= 0x17 )
         {
             uint64_t msr_val;
 
diff --git a/xen/include/asm-x86/cpuid.h b/xen/include/asm-x86/cpuid.h
index b359b38..c56190b 100644
--- a/xen/include/asm-x86/cpuid.h
+++ b/xen/include/asm-x86/cpuid.h
@@ -107,7 +107,7 @@ struct cpuid_policy
             uint32_t max_leaf, /* b */:32, /* c */:32, /* d */:32;
 
             /* Leaf 0x1 - Family/model/stepping and features. */
-            uint32_t /* a */:32, /* b */:32;
+            uint32_t raw_fms, /* b */:32;
             union {
                 uint32_t _1c;
                 struct { DECL_BITFIELD(1c); };
diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index eb6227d..82296c8 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -338,9 +338,7 @@ struct arch_domain
     bool_t auto_unmask;
 
     /* Values snooped from updates to cpuids[] (below). */
-    u8 x86;                  /* CPU family */
     u8 x86_vendor;           /* CPU vendor */
-    u8 x86_model;            /* CPU model */
 
     /*
      * The width of the FIP/FDP register in the FPU that needs to be
diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h
index b130f47..3b859a5 100644
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -625,7 +625,28 @@ enum get_cpu_vendor {
 };
 
 int get_cpu_vendor(uint32_t b, uint32_t c, uint32_t d, enum get_cpu_vendor 
mode);
-uint8_t get_cpu_family(uint32_t raw, uint8_t *model, uint8_t *stepping);
+
+static inline uint8_t get_cpu_family(uint32_t raw, uint8_t *model,
+                                     uint8_t *stepping)
+{
+    uint8_t fam = (raw >> 8) & 0xf;
+
+    if ( fam == 0xf )
+        fam += (raw >> 20) & 0xff;
+
+    if ( model )
+    {
+        uint8_t mod = (raw >> 4) & 0xf;
+
+        if ( fam >= 0x6 )
+            mod |= (raw >> 12) & 0xf0;
+
+        *model = mod;
+    }
+    if ( stepping )
+        *stepping = raw & 0xf;
+    return fam;
+}
 
 #endif /* !__ASSEMBLY__ */
 
-- 
2.1.4


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