Re: [Xen-devel] [PATCH v2] x86/xsave: simplify xcomp_bv initialization

2016-01-13 Thread Andrew Cooper
On 13/01/16 07:30, Jan Beulich wrote:
> This simplifies a number of pointless conditionals: Bits 0 and 1 of
> xcomp_bv don't matter anyway, and as long as none of bits 2..62 are
> set, setting bit 63 is pointless too unless XSAVES is in use.
>
> Signed-off-by: Jan Beulich 

Reviewed-by: Andrew Cooper 

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[Xen-devel] [PATCH v2] x86/xsave: simplify xcomp_bv initialization

2016-01-12 Thread Jan Beulich
This simplifies a number of pointless conditionals: Bits 0 and 1 of
xcomp_bv don't matter anyway, and as long as none of bits 2..62 are
set, setting bit 63 is pointless too unless XSAVES is in use.

Signed-off-by: Jan Beulich 
---
v2: Retain setting of bit 63 on XSAVES-capable systems.

--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -922,9 +922,8 @@ int arch_set_info_guest(
 if ( v->arch.xsave_area )
 {
 v->arch.xsave_area->xsave_hdr.xstate_bv = XSTATE_FP_SSE;
-if ( cpu_has_xsaves || cpu_has_xsavec )
-v->arch.xsave_area->xsave_hdr.xcomp_bv = XSTATE_FP_SSE |
- 
XSTATE_COMPACTION_ENABLED;
+v->arch.xsave_area->xsave_hdr.xcomp_bv =
+cpu_has_xsaves ? XSTATE_COMPACTION_ENABLED : 0;
 }
 }
 else if ( v->arch.xsave_area )
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2094,9 +2094,8 @@ static int hvm_load_cpu_ctxt(struct doma
 
 memcpy(v->arch.xsave_area, ctxt.fpu_regs, sizeof(ctxt.fpu_regs));
 xsave_area->xsave_hdr.xstate_bv = XSTATE_FP_SSE;
-if ( cpu_has_xsaves || cpu_has_xsavec )
-xsave_area->xsave_hdr.xcomp_bv = XSTATE_FP_SSE |
- XSTATE_COMPACTION_ENABLED;
+xsave_area->xsave_hdr.xcomp_bv =
+cpu_has_xsaves ? XSTATE_COMPACTION_ENABLED : 0;
 }
 else
 memcpy(v->arch.fpu_ctxt, ctxt.fpu_regs, sizeof(ctxt.fpu_regs));
@@ -5455,9 +5454,8 @@ void hvm_vcpu_reset_state(struct vcpu *v
 if ( v->arch.xsave_area )
 {
 v->arch.xsave_area->xsave_hdr.xstate_bv = XSTATE_FP;
-if ( cpu_has_xsaves || cpu_has_xsavec )
-v->arch.xsave_area->xsave_hdr.xcomp_bv = XSTATE_FP |
- XSTATE_COMPACTION_ENABLED;
+v->arch.xsave_area->xsave_hdr.xcomp_bv =
+cpu_has_xsaves ? XSTATE_COMPACTION_ENABLED : 0;
 }
 
 v->arch.vgc_flags = VGCF_online;
--- a/xen/arch/x86/i387.c
+++ b/xen/arch/x86/i387.c
@@ -272,7 +272,7 @@ int vcpu_init_fpu(struct vcpu *v)
 if ( v->arch.xsave_area )
 {
 v->arch.fpu_ctxt = &v->arch.xsave_area->fpu_sse;
-if ( cpu_has_xsaves || cpu_has_xsavec )
+if ( cpu_has_xsaves )
 v->arch.xsave_area->xsave_hdr.xcomp_bv = XSTATE_COMPACTION_ENABLED;
 }
 else



x86/xsave: simplify xcomp_bv initialization

This simplifies a number of pointless conditionals: Bits 0 and 1 of
xcomp_bv don't matter anyway, and as long as none of bits 2..62 are
set, setting bit 63 is pointless too unless XSAVES is in use.

Signed-off-by: Jan Beulich 
---
v2: Retain setting of bit 63 on XSAVES-capable systems.

--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -922,9 +922,8 @@ int arch_set_info_guest(
 if ( v->arch.xsave_area )
 {
 v->arch.xsave_area->xsave_hdr.xstate_bv = XSTATE_FP_SSE;
-if ( cpu_has_xsaves || cpu_has_xsavec )
-v->arch.xsave_area->xsave_hdr.xcomp_bv = XSTATE_FP_SSE |
- 
XSTATE_COMPACTION_ENABLED;
+v->arch.xsave_area->xsave_hdr.xcomp_bv =
+cpu_has_xsaves ? XSTATE_COMPACTION_ENABLED : 0;
 }
 }
 else if ( v->arch.xsave_area )
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2094,9 +2094,8 @@ static int hvm_load_cpu_ctxt(struct doma
 
 memcpy(v->arch.xsave_area, ctxt.fpu_regs, sizeof(ctxt.fpu_regs));
 xsave_area->xsave_hdr.xstate_bv = XSTATE_FP_SSE;
-if ( cpu_has_xsaves || cpu_has_xsavec )
-xsave_area->xsave_hdr.xcomp_bv = XSTATE_FP_SSE |
- XSTATE_COMPACTION_ENABLED;
+xsave_area->xsave_hdr.xcomp_bv =
+cpu_has_xsaves ? XSTATE_COMPACTION_ENABLED : 0;
 }
 else
 memcpy(v->arch.fpu_ctxt, ctxt.fpu_regs, sizeof(ctxt.fpu_regs));
@@ -5455,9 +5454,8 @@ void hvm_vcpu_reset_state(struct vcpu *v
 if ( v->arch.xsave_area )
 {
 v->arch.xsave_area->xsave_hdr.xstate_bv = XSTATE_FP;
-if ( cpu_has_xsaves || cpu_has_xsavec )
-v->arch.xsave_area->xsave_hdr.xcomp_bv = XSTATE_FP |
- XSTATE_COMPACTION_ENABLED;
+v->arch.xsave_area->xsave_hdr.xcomp_bv =
+cpu_has_xsaves ? XSTATE_COMPACTION_ENABLED : 0;
 }
 
 v->arch.vgc_flags = VGCF_online;
--- a/xen/arch/x86/i387.c
+++ b/xen/arch/x86/i387.c
@@ -272,7 +272,7 @@ int vcpu_init_fpu(struct vcpu *v)
 if ( v->arch.xsave_area )
 {
 v->arch.fpu_ctxt = &v->arch.xsave_area->fpu_sse;
-if ( cpu_has_xsaves || cpu_has_xsavec )
+if ( cpu_has_xsaves )
 v->arch.xsave_area->xsave_hdr.xcomp_bv = XSTATE_COMPACTION_ENABLED;
 }
 else
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