x86/xsave: remove xfeat_mask checking from validate_xstate()

validate_xsave() is called codepaths which load new vcpu xsave state from
XEN_DOMCTL_{setvcpuextstate,sethvmcontext}, usually as part of migration.  In
both cases, this is the xfeature_mask of the saving Xen rather than the
restoring Xen.

Given that the xsave state itself is checked for consistency and validity on
the current cpu, checking whether it was valid for the cpu before migration is
not interesting (or indeed relevant, as the error can't be distinguished from
the other validity checking).

This change removes the need to pass the saving Xen's xfeature_mask,
simplifying the toolstack code and migration stream format in this area.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index f8b0a7935bd0ee8d3ee4689ef02232ad0ac653cd..1285dd05c0f72d54439b27dded5b20d7a5854dbe 100644 (file)
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1247,8 +1247,7 @@ long arch_do_domctl(
             {
                 if ( evc->size >= 2 * sizeof(uint64_t) + XSTATE_AREA_MIN_SIZE )
                     ret = validate_xstate(_xcr0, _xcr0_accum,
-                                          _xsave_area->xsave_hdr.xstate_bv,
-                                          evc->xfeature_mask);
+                                          _xsave_area->xsave_hdr.xstate_bv);
             }
             else if ( !_xcr0 )
                 ret = 0;

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 59836a11b643c8da95c8b6af85ab7b9bce3b9b5c..163e62a589c33c3aa97feeb7dfe8c6839cfc8ca0 100644 (file)
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1992,8 +1992,7 @@ static int hvm_load_cpu_xsave_states(struct domain *d, hvm_domain_context_t *h)
     h->cur += desc->length;
 
     err = validate_xstate(ctxt->xcr0, ctxt->xcr0_accum,
-                          ctxt->save_area.xsave_hdr.xstate_bv,
-                          ctxt->xfeature_mask);
+                          ctxt->save_area.xsave_hdr.xstate_bv);
     if ( err )
     {
         printk(XENLOG_G_WARNING

diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c
index 7d9b92b552b186411dbd07e772437760dfcd6c53..e202344613a961a86af178ea76924eb98a3534e1 100644 (file)
--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -346,10 +346,9 @@ static bool_t valid_xcr0(u64 xcr0)
     return !(xcr0 & XSTATE_BNDREGS) == !(xcr0 & XSTATE_BNDCSR);
 }
 
-int validate_xstate(u64 xcr0, u64 xcr0_accum, u64 xstate_bv, u64 xfeat_mask)
+int validate_xstate(u64 xcr0, u64 xcr0_accum, u64 xstate_bv)
 {
-    if ( (xcr0_accum & ~xfeat_mask) ||
-         (xstate_bv & ~xcr0_accum) ||
+    if ( (xstate_bv & ~xcr0_accum) ||
          (xcr0 & ~xcr0_accum) ||
          !valid_xcr0(xcr0) ||
          !valid_xcr0(xcr0_accum) )

diff --git a/xen/include/asm-x86/xstate.h b/xen/include/asm-x86/xstate.h
index 1a92ac3d2dcfb56ed5ff155b31b8ba39fda93efd..8d213490be37b2cffbc9961b27f3ffc13218692c 100644 (file)
--- a/xen/include/asm-x86/xstate.h
+++ b/xen/include/asm-x86/xstate.h
@@ -81,8 +81,7 @@ uint64_t get_xcr0(void);
 void xsave(struct vcpu *v, uint64_t mask);
 void xrstor(struct vcpu *v, uint64_t mask);
 bool_t xsave_enabled(const struct vcpu *v);
-int __must_check validate_xstate(u64 xcr0, u64 xcr0_accum, u64 xstate_bv,
-                                 u64 xfeat_mask);
+int __must_check validate_xstate(u64 xcr0, u64 xcr0_accum, u64 xstate_bv);
 int __must_check handle_xsetbv(u32 index, u64 new_bv);
 
 /* extended state init and cleanup functions */

diff --git a/xen/include/public/arch-x86/hvm/save.h b/xen/include/public/arch-x86/hvm/save.h
index 5a13795108e72adef9a5dc12dba3801c74fe94f5..16d85a3e3e1ca373b133bbd942a8c54d186af49c 100644 (file)
--- a/xen/include/public/arch-x86/hvm/save.h
+++ b/xen/include/public/arch-x86/hvm/save.h
@@ -544,7 +544,7 @@ DECLARE_HVM_SAVE_TYPE(MTRR, 14, struct hvm_hw_mtrr);
  */
 
 struct hvm_hw_cpu_xsave {
-    uint64_t xfeature_mask;
+    uint64_t xfeature_mask;        /* Ignored */
     uint64_t xcr0;                 /* Updated by XSETBV */
     uint64_t xcr0_accum;           /* Updated by XSETBV */
     struct {

diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 565fa4c91c786af4bd490e5ac38041bf51e76e0f..385b0539587569f4b779d0e2906dc457ba16e870 100644 (file)
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -839,7 +839,7 @@ struct xen_domctl_vcpuextstate {
     /* IN: VCPU that this call applies to. */
     uint32_t         vcpu;
     /*
-     * SET: xfeature support mask of struct (IN)
+     * SET: Ignored.
      * GET: xfeature support mask of struct (IN/OUT)
      * xfeature mask is served as identifications of the saving format
      * so that compatible CPUs can have a check on format to decide