[Xen-devel] [PATCH] libx86: Introduce wrappers for extracting XCR0/XSS from a cpuid policy

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

This avoids opencoding the slightly-awkward logic.  More uses of these
wrappers will be introduced shortly.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>

I've decided to introduce this patch ahead of "[PATCH] libx86: Elide more
empty CPUID leaves when serialising a policy" (which simplifies the xstate
hunk a little) as I've found yet more cases where I need to use
cpuid_policy_xstates(), and opencoding them all seemed very silly.
---
 xen/arch/x86/xstate.c           |  8 ++------
 xen/include/xen/lib/x86/cpuid.h | 12 ++++++++++++
 xen/lib/x86/cpuid.c             |  3 +--
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c
index 3da609a..04da569 100644
--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -660,9 +660,7 @@ static bool valid_xcr0(u64 xcr0)
 int validate_xstate(const struct domain *d, uint64_t xcr0, uint64_t xcr0_accum,
                     const struct xsave_hdr *hdr)
 {
-    const struct cpuid_policy *cp = d->arch.cpuid;
-    uint64_t xcr0_max =
-        ((uint64_t)cp->xstate.xcr0_high << 32) | cp->xstate.xcr0_low;
+    uint64_t xcr0_max = cpuid_policy_xcr0(d->arch.cpuid);
     unsigned int i;
 
     if ( (hdr->xstate_bv & ~xcr0_accum) ||
@@ -686,9 +684,7 @@ int validate_xstate(const struct domain *d, uint64_t xcr0, 
uint64_t xcr0_accum,
 int handle_xsetbv(u32 index, u64 new_bv)
 {
     struct vcpu *curr = current;
-    const struct cpuid_policy *cp = curr->domain->arch.cpuid;
-    uint64_t xcr0_max =
-        ((uint64_t)cp->xstate.xcr0_high << 32) | cp->xstate.xcr0_low;
+    uint64_t xcr0_max = cpuid_policy_xcr0(curr->domain->arch.cpuid);
     u64 mask;
 
     if ( index != XCR_XFEATURE_ENABLED_MASK )
diff --git a/xen/include/xen/lib/x86/cpuid.h b/xen/include/xen/lib/x86/cpuid.h
index 252d2c9..ea4db5b 100644
--- a/xen/include/xen/lib/x86/cpuid.h
+++ b/xen/include/xen/lib/x86/cpuid.h
@@ -308,6 +308,18 @@ static inline void cpuid_featureset_to_policy(
     p->feat._7a1  = fs[FEATURESET_7a1];
 }
 
+static inline uint64_t cpuid_policy_xcr0(const struct cpuid_policy *p)
+{
+    return ((uint64_t)p->xstate.xcr0_high << 32) | p->xstate.xcr0_low;
+}
+
+static inline uint64_t cpuid_policy_xstates(const struct cpuid_policy *p)
+{
+    uint64_t val = p->xstate.xcr0_high | p->xstate.xss_high;
+
+    return (val << 32) | p->xstate.xcr0_low | p->xstate.xss_low;
+}
+
 const uint32_t *x86_cpuid_lookup_deep_deps(uint32_t feature);
 
 /**
diff --git a/xen/lib/x86/cpuid.c b/xen/lib/x86/cpuid.c
index 23619c7..74c5b18 100644
--- a/xen/lib/x86/cpuid.c
+++ b/xen/lib/x86/cpuid.c
@@ -144,8 +144,7 @@ void x86_cpuid_policy_fill_native(struct cpuid_policy *p)
         cpuid_count_leaf(0xd, 0, &p->xstate.raw[0]);
         cpuid_count_leaf(0xd, 1, &p->xstate.raw[1]);
 
-        xstates  = ((uint64_t)(p->xstate.xcr0_high | p->xstate.xss_high) << 
32);
-        xstates |=            (p->xstate.xcr0_low  | p->xstate.xss_low);
+        xstates = cpuid_policy_xstates(p);
 
         for ( i = 2; i < min_t(unsigned int, 63,
                                ARRAY_SIZE(p->xstate.raw)); ++i )
-- 
2.1.4


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