[PATCH v2 11/30] xen/x86: Calculate maximum host and guest featuresets

[Andrew Cooper <andrew.cooper3@citrix.com>]

All of this information will be used by the toolstack to make informed
levelling decisions for VMs, and by Xen to sanity check toolstack-provided
information.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
---
 xen/arch/x86/cpuid.c        | 152 ++++++++++++++++++++++++++++++++++++++++++++
 xen/arch/x86/setup.c        |   3 +
 xen/include/asm-x86/cpuid.h |  17 +++++
 3 files changed, 172 insertions(+)

diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
index 30a3392..1af0e6c 100644
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -1,13 +1,165 @@
 #include <xen/lib.h>
 #include <asm/cpuid.h>
+#include <asm/hvm/hvm.h>
+#include <asm/hvm/vmx/vmcs.h>
+#include <asm/processor.h>
+
+#define COMMON_1D INIT_COMMON_FEATURES
 
 const uint32_t known_features[] = INIT_KNOWN_FEATURES;
 const uint32_t inverted_features[] = INIT_INVERTED_FEATURES;
 
+static const uint32_t pv_featuremask[] = INIT_PV_FEATURES;
+static const uint32_t hvm_shadow_featuremask[] = INIT_HVM_SHADOW_FEATURES;
+static const uint32_t hvm_hap_featuremask[] = INIT_HVM_HAP_FEATURES;
+
+uint32_t __read_mostly raw_featureset[FSCAPINTS];
+uint32_t __read_mostly host_featureset[FSCAPINTS];
+uint32_t __read_mostly pv_featureset[FSCAPINTS];
+uint32_t __read_mostly hvm_featureset[FSCAPINTS];
+
+static void sanitise_featureset(uint32_t *fs)
+{
+    unsigned int i;
+
+    for ( i = 0; i < FSCAPINTS; ++i )
+    {
+        /* Clamp to known mask. */
+        fs[i] &= known_features[i];
+    }
+
+    switch ( boot_cpu_data.x86_vendor )
+    {
+    case X86_VENDOR_INTEL:
+        /* Intel clears the common bits in e1d. */
+        fs[FEATURESET_e1d] &= ~COMMON_1D;
+        break;
+
+    case X86_VENDOR_AMD:
+        /* AMD duplicates the common bits between 1d and e1d. */
+        fs[FEATURESET_e1d] = ((fs[FEATURESET_1d]  &  COMMON_1D) |
+                              (fs[FEATURESET_e1d] & ~COMMON_1D));
+        break;
+    }
+}
+
+static void calculate_raw_featureset(void)
+{
+    unsigned int i, max, tmp;
+
+    max = cpuid_eax(0);
+
+    if ( max >= 1 )
+        cpuid(0x1, &tmp, &tmp,
+              &raw_featureset[FEATURESET_1c],
+              &raw_featureset[FEATURESET_1d]);
+    if ( max >= 7 )
+        cpuid_count(0x7, 0, &tmp,
+                    &raw_featureset[FEATURESET_7b0],
+                    &raw_featureset[FEATURESET_7c0],
+                    &tmp);
+    if ( max >= 0xd )
+        cpuid_count(0xd, 1,
+                    &raw_featureset[FEATURESET_Da1],
+                    &tmp, &tmp, &tmp);
+
+    max = cpuid_eax(0x80000000);
+    if ( max >= 0x80000001 )
+        cpuid(0x80000001, &tmp, &tmp,
+              &raw_featureset[FEATURESET_e1c],
+              &raw_featureset[FEATURESET_e1d]);
+    if ( max >= 0x80000007 )
+        cpuid(0x80000007, &tmp, &tmp, &tmp,
+              &raw_featureset[FEATURESET_e7d]);
+    if ( max >= 0x80000008 )
+        cpuid(0x80000008, &tmp,
+              &raw_featureset[FEATURESET_e8b],
+              &tmp, &tmp);
+
+    for ( i = 0; i < ARRAY_SIZE(raw_featureset); ++i )
+        raw_featureset[i] ^= inverted_features[i];
+}
+
+static void calculate_host_featureset(void)
+{
+    memcpy(host_featureset, boot_cpu_data.x86_capability,
+           sizeof(host_featureset));
+}
+
+static void calculate_pv_featureset(void)
+{
+    unsigned int i;
+
+    for ( i = 0; i < ARRAY_SIZE(pv_featureset); ++i )
+        pv_featureset[i] = host_featureset[i] & pv_featuremask[i];
+
+    /* Unconditionally claim to be able to set the hypervisor bit. */
+    __set_bit(X86_FEATURE_HYPERVISOR, pv_featureset);
+
+    sanitise_featureset(pv_featureset);
+}
+
+static void calculate_hvm_featureset(void)
+{
+    unsigned int i;
+    const uint32_t *hvm_featuremask;
+
+    if ( !hvm_enabled )
+        return;
+
+    hvm_featuremask = hvm_funcs.hap_supported ?
+        hvm_hap_featuremask : hvm_shadow_featuremask;
+
+    for ( i = 0; i < ARRAY_SIZE(hvm_featureset); ++i )
+        hvm_featureset[i] = host_featureset[i] & hvm_featuremask[i];
+
+    /* Unconditionally claim to be able to set the hypervisor bit. */
+    __set_bit(X86_FEATURE_HYPERVISOR, hvm_featureset);
+
+    /*
+     * On AMD, PV guests are entirely unable to use 'sysenter' as Xen runs in
+     * long mode (and init_amd() has cleared it out of host capabilities), but
+     * HVM guests are able if running in protected mode.
+     */
+    if ( (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
+         test_bit(X86_FEATURE_SEP, raw_featureset) )
+        __set_bit(X86_FEATURE_SEP, hvm_featureset);
+
+    /*
+     * With VT-x, some features are only supported by Xen if dedicated
+     * hardware support is also available.
+     */
+    if ( cpu_has_vmx )
+    {
+        if ( !(vmx_vmexit_control & VM_EXIT_CLEAR_BNDCFGS) ||
+             !(vmx_vmentry_control & VM_ENTRY_LOAD_BNDCFGS) )
+            __clear_bit(X86_FEATURE_MPX, hvm_featureset);
+
+        if ( !cpu_has_vmx_xsaves )
+            __clear_bit(X86_FEATURE_XSAVES, hvm_featureset);
+
+        if ( !cpu_has_vmx_pcommit )
+            __clear_bit(X86_FEATURE_PCOMMIT, hvm_featureset);
+    }
+
+    sanitise_featureset(pv_featureset);
+}
+
+void calculate_featuresets(void)
+{
+    calculate_raw_featureset();
+    calculate_host_featureset();
+    calculate_pv_featureset();
+    calculate_hvm_featureset();
+}
+
 static void __maybe_unused build_assertions(void)
 {
     BUILD_BUG_ON(ARRAY_SIZE(known_features) != FSCAPINTS);
     BUILD_BUG_ON(ARRAY_SIZE(inverted_features) != FSCAPINTS);
+    BUILD_BUG_ON(ARRAY_SIZE(pv_featuremask) != FSCAPINTS);
+    BUILD_BUG_ON(ARRAY_SIZE(hvm_shadow_featuremask) != FSCAPINTS);
+    BUILD_BUG_ON(ARRAY_SIZE(hvm_hap_featuremask) != FSCAPINTS);
 }
 
 /*
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 76c7b0f..50e4e51 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -50,6 +50,7 @@
 #include <asm/nmi.h>
 #include <asm/alternative.h>
 #include <asm/mc146818rtc.h>
+#include <asm/cpuid.h>
 
 /* opt_nosmp: If true, secondary processors are ignored. */
 static bool_t __initdata opt_nosmp;
@@ -1437,6 +1438,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
                "Multiple initrd candidates, picking module #%u\n",
                initrdidx);
 
+    calculate_featuresets();
+
     /*
      * Temporarily clear SMAP in CR4 to allow user-accesses in construct_dom0().
      * This saves a large number of corner cases interactions with
diff --git a/xen/include/asm-x86/cpuid.h b/xen/include/asm-x86/cpuid.h
index 341dbc1..18ba95b 100644
--- a/xen/include/asm-x86/cpuid.h
+++ b/xen/include/asm-x86/cpuid.h
@@ -5,12 +5,29 @@
 
 #define FSCAPINTS FEATURESET_NR_ENTRIES
 
+#define FEATURESET_1d     0 /* 0x00000001.edx      */
+#define FEATURESET_1c     1 /* 0x00000001.ecx      */
+#define FEATURESET_e1d    2 /* 0x80000001.edx      */
+#define FEATURESET_e1c    3 /* 0x80000001.ecx      */
+#define FEATURESET_Da1    4 /* 0x0000000d:1.eax    */
+#define FEATURESET_7b0    5 /* 0x00000007:0.ebx    */
+#define FEATURESET_7c0    6 /* 0x00000007:0.ecx    */
+#define FEATURESET_e7d    7 /* 0x80000007.edx      */
+#define FEATURESET_e8b    8 /* 0x80000008.ebx      */
+
 #ifndef __ASSEMBLY__
 #include <xen/types.h>
 
 extern const uint32_t known_features[FSCAPINTS];
 extern const uint32_t inverted_features[FSCAPINTS];
 
+extern uint32_t raw_featureset[FSCAPINTS];
+extern uint32_t host_featureset[FSCAPINTS];
+extern uint32_t pv_featureset[FSCAPINTS];
+extern uint32_t hvm_featureset[FSCAPINTS];
+
+void calculate_featuresets(void);
+
 #endif /* __ASSEMBLY__ */
 #endif /* !__X86_CPUID_H__ */
 
-- 
2.1.4