[Xen-devel] [PATCH v2 2/5] x86/xsave: enable support for new ISA extensions

["Jan Beulich" <JBeulich@xxxxxxxx>]

Intel has released new version of Intel Architecture Instruction Set
Extensions Programming Reference, adding new features like AVX-512,
MPX, etc. Refer to
http://download-software.intel.com/sites/default/files/319433-015.pdf 

This patch adds support for these new instruction set extensions
without enabling this support for guest use, yet.

It also adjusts XCR0 validation, at once fixing the definition of
XSTATE_ALL (which is not supposed to include bit 63).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -253,7 +253,7 @@ void xstate_free_save_area(struct vcpu *
 /* Collect the information of processor's extended state */
 void xstate_init(bool_t bsp)
 {
-    u32 eax, ebx, ecx, edx, min_size;
+    u32 eax, ebx, ecx, edx;
     u64 feature_mask;
 
     if ( boot_cpu_data.cpuid_level < XSTATE_CPUID )
@@ -269,12 +269,6 @@ void xstate_init(bool_t bsp)
     BUG_ON((eax & XSTATE_YMM) && !(eax & XSTATE_SSE));
     feature_mask = (((u64)edx << 32) | eax) & XCNTXT_MASK;
 
-    /* FP/SSE, XSAVE.HEADER, YMM */
-    min_size =  XSTATE_AREA_MIN_SIZE;
-    if ( eax & XSTATE_YMM )
-        min_size += XSTATE_YMM_SIZE;
-    BUG_ON(ecx < min_size);
-
     /*
      * Set CR4_OSXSAVE and run "cpuid" to get xsave_cntxt_size.
      */
@@ -327,14 +321,38 @@ unsigned int xstate_ctxt_size(u64 xcr0)
     return ebx;
 }
 
+static bool_t valid_xcr0(u64 xcr0)
+{
+    /* FP must be unconditionally set. */
+    if ( !(xcr0 & XSTATE_FP) )
+        return 0;
+
+    /* YMM depends on SSE. */
+    if ( (xcr0 & XSTATE_YMM) && !(xcr0 & XSTATE_SSE) )
+        return 0;
+
+    if ( xcr0 & (XSTATE_OPMASK | XSTATE_ZMM | XSTATE_HI_ZMM) )
+    {
+        /* OPMASK, ZMM, and HI_ZMM require YMM. */
+        if ( !(xcr0 & XSTATE_YMM) )
+            return 0;
+
+        /* OPMASK, ZMM, and HI_ZMM must be the same. */
+        if ( ~xcr0 & (XSTATE_OPMASK | XSTATE_ZMM | XSTATE_HI_ZMM) )
+            return 0;
+    }
+
+    /* BNDREGS and BNDCSR must be the same. */
+    return !(xcr0 & XSTATE_BNDREGS) == !(xcr0 & XSTATE_BNDCSR);
+}
+
 int validate_xstate(u64 xcr0, u64 xcr0_accum, u64 xstate_bv, u64 xfeat_mask)
 {
     if ( (xcr0_accum & ~xfeat_mask) ||
          (xstate_bv & ~xcr0_accum) ||
          (xcr0 & ~xcr0_accum) ||
-         !(xcr0 & XSTATE_FP) ||
-         ((xcr0 & XSTATE_YMM) && !(xcr0 & XSTATE_SSE)) ||
-         ((xcr0_accum & XSTATE_YMM) && !(xcr0_accum & XSTATE_SSE)) )
+         !valid_xcr0(xcr0) ||
+         !valid_xcr0(xcr0_accum) )
         return -EINVAL;
 
     if ( xcr0_accum & ~xfeature_mask )
@@ -351,10 +369,7 @@ int handle_xsetbv(u32 index, u64 new_bv)
     if ( index != XCR_XFEATURE_ENABLED_MASK )
         return -EOPNOTSUPP;
 
-    if ( (new_bv & ~xfeature_mask) || !(new_bv & XSTATE_FP) )
-        return -EINVAL;
-
-    if ( (new_bv & XSTATE_YMM) && !(new_bv & XSTATE_SSE) )
+    if ( (new_bv & ~xfeature_mask) || !valid_xcr0(new_bv) )
         return -EINVAL;
 
     if ( !set_xcr0(new_bv) )
@@ -364,6 +379,10 @@ int handle_xsetbv(u32 index, u64 new_bv)
     curr->arch.xcr0 = new_bv;
     curr->arch.xcr0_accum |= new_bv;
 
+    /* LWP sets nonlazy_xstate_used independently. */
+    if ( new_bv & (XSTATE_NONLAZY & ~XSTATE_LWP) )
+        curr->arch.nonlazy_xstate_used = 1;
+
     mask &= curr->fpu_dirtied ? ~XSTATE_FP_SSE : XSTATE_NONLAZY;
     if ( mask )
     {
--- a/xen/include/asm-x86/xstate.h
+++ b/xen/include/asm-x86/xstate.h
@@ -20,18 +20,23 @@
 #define XCR_XFEATURE_ENABLED_MASK 0x00000000  /* index of XCR0 */
 
 #define XSTATE_YMM_SIZE           256
-#define XSTATE_YMM_OFFSET         XSAVE_AREA_MIN_SIZE
 #define XSTATE_AREA_MIN_SIZE      (512 + 64)  /* FP/SSE + XSAVE.HEADER */
 
 #define XSTATE_FP      (1ULL << 0)
 #define XSTATE_SSE     (1ULL << 1)
 #define XSTATE_YMM     (1ULL << 2)
+#define XSTATE_BNDREGS (1ULL << 3)
+#define XSTATE_BNDCSR  (1ULL << 4)
+#define XSTATE_OPMASK  (1ULL << 5)
+#define XSTATE_ZMM     (1ULL << 6)
+#define XSTATE_HI_ZMM  (1ULL << 7)
 #define XSTATE_LWP     (1ULL << 62) /* AMD lightweight profiling */
 #define XSTATE_FP_SSE  (XSTATE_FP | XSTATE_SSE)
-#define XCNTXT_MASK    (XSTATE_FP | XSTATE_SSE | XSTATE_YMM | XSTATE_LWP)
+#define XCNTXT_MASK    (XSTATE_FP | XSTATE_SSE | XSTATE_YMM | XSTATE_OPMASK | \
+                        XSTATE_ZMM | XSTATE_HI_ZMM | XSTATE_NONLAZY)
 
-#define XSTATE_ALL     (~0)
-#define XSTATE_NONLAZY (XSTATE_LWP)
+#define XSTATE_ALL     (~(1ULL << 63))
+#define XSTATE_NONLAZY (XSTATE_LWP | XSTATE_BNDREGS | XSTATE_BNDCSR)
 #define XSTATE_LAZY    (XSTATE_ALL & ~XSTATE_NONLAZY)
 
 extern u64 xfeature_mask;

Attachment: x86-xsave-more.patch
Description: Text document

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