90 lines
2.5 KiB
Diff
90 lines
2.5 KiB
Diff
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x86: don't leak ST(n)/XMMn values to domains first using them
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FNINIT doesn't alter these registers, and hence using it is
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insufficient to initialize a guest's initial state.
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This is XSA-165.
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
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Index: xen-4.6.0-testing/xen/arch/x86/domain.c
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===================================================================
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--- xen-4.6.0-testing.orig/xen/arch/x86/domain.c
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+++ xen-4.6.0-testing/xen/arch/x86/domain.c
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@@ -851,6 +851,17 @@ int arch_set_info_guest(
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if ( v->arch.xsave_area )
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v->arch.xsave_area->xsave_hdr.xstate_bv = XSTATE_FP_SSE;
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}
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+ else if ( v->arch.xsave_area )
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+ memset(&v->arch.xsave_area->xsave_hdr, 0,
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+ sizeof(v->arch.xsave_area->xsave_hdr));
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+ else
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+ {
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+ typeof(v->arch.xsave_area->fpu_sse) *fpu_sse = v->arch.fpu_ctxt;
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+
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+ memset(fpu_sse, 0, sizeof(*fpu_sse));
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+ fpu_sse->fcw = FCW_DEFAULT;
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+ fpu_sse->mxcsr = MXCSR_DEFAULT;
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+ }
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if ( !compat )
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{
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Index: xen-4.6.0-testing/xen/arch/x86/i387.c
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===================================================================
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--- xen-4.6.0-testing.orig/xen/arch/x86/i387.c
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+++ xen-4.6.0-testing/xen/arch/x86/i387.c
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@@ -17,19 +17,6 @@
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#include <asm/xstate.h>
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#include <asm/asm_defns.h>
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-static void fpu_init(void)
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-{
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- unsigned long val;
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-
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- asm volatile ( "fninit" );
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- if ( cpu_has_xmm )
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- {
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- /* load default value into MXCSR control/status register */
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- val = MXCSR_DEFAULT;
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- asm volatile ( "ldmxcsr %0" : : "m" (val) );
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- }
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-}
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-
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/*******************************/
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/* FPU Restore Functions */
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/*******************************/
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@@ -248,15 +235,8 @@ void vcpu_restore_fpu_lazy(struct vcpu *
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if ( cpu_has_xsave )
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fpu_xrstor(v, XSTATE_LAZY);
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- else if ( v->fpu_initialised )
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- {
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- if ( cpu_has_fxsr )
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- fpu_fxrstor(v);
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- else
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- fpu_frstor(v);
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- }
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else
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- fpu_init();
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+ fpu_fxrstor(v);
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v->fpu_initialised = 1;
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v->fpu_dirtied = 1;
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@@ -313,7 +293,14 @@ int vcpu_init_fpu(struct vcpu *v)
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else
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{
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v->arch.fpu_ctxt = _xzalloc(sizeof(v->arch.xsave_area->fpu_sse), 16);
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- if ( !v->arch.fpu_ctxt )
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+ if ( v->arch.fpu_ctxt )
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+ {
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+ typeof(v->arch.xsave_area->fpu_sse) *fpu_sse = v->arch.fpu_ctxt;
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+
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+ fpu_sse->fcw = FCW_DEFAULT;
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+ fpu_sse->mxcsr = MXCSR_DEFAULT;
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+ }
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+ else
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rc = -ENOMEM;
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}
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