86 lines
2.9 KiB
Diff
86 lines
2.9 KiB
Diff
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# HG changeset patch
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# User Jan Beulich <jbeulich@suse.com>
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# Date 1324046740 -3600
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# Node ID 1452fb248cd513832cfbbd1100b9b72a0dde7ea6
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# Parent 01c8b27e3d7d4ad2b469be9922bb04b5eb0195e8
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x86/emulator: workaround for AMD erratum 573
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The only cases where we might end up emulating fsincos (as any other
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x87 operations without memory operands) are
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- when a HVM guest is in real mode (not applicable on AMD)
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- between two half page table updates in PAE mode (unlikely, and not
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doing the emulation here does affect only performance, not
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correctness)
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- when a guest maliciously (or erroneously) modifies an (MMIO or page
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table update) instruction under emulation (unspecified behavior)
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Hence, in order to avoid the erratum to cause harm to the entire host,
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don't emulate fsincos on the affected AMD CPU families.
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Acked-by: Keir Fraser <keir@xen.org>
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--- a/tools/tests/x86_emulator/x86_emulate.c
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+++ b/tools/tests/x86_emulator/x86_emulate.c
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@@ -3,5 +3,7 @@
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#include <string.h>
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#include <public/xen.h>
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+#define cpu_has_amd_erratum(nr) 0
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+
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#include "x86_emulate/x86_emulate.h"
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#include "x86_emulate/x86_emulate.c"
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--- a/xen/arch/x86/x86_emulate.c
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+++ b/xen/arch/x86/x86_emulate.c
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@@ -10,8 +10,15 @@
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*/
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#include <asm/x86_emulate.h>
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+#include <asm/processor.h> /* current_cpu_info */
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+#include <asm/amd.h> /* cpu_has_amd_erratum() */
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/* Avoid namespace pollution. */
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#undef cmpxchg
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+#undef cpuid
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+#undef wbinvd
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+
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+#define cpu_has_amd_erratum(nr) \
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+ cpu_has_amd_erratum(¤t_cpu_data, AMD_ERRATUM_##nr)
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#include "x86_emulate/x86_emulate.c"
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--- a/xen/arch/x86/x86_emulate/x86_emulate.c
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+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
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@@ -2621,6 +2621,9 @@ x86_emulate(
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case 0xd9: /* FPU 0xd9 */
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switch ( modrm )
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{
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+ case 0xfb: /* fsincos */
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+ fail_if(cpu_has_amd_erratum(573));
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+ /* fall through */
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case 0xc0 ... 0xc7: /* fld %stN */
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case 0xc8 ... 0xcf: /* fxch %stN */
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case 0xd0: /* fnop */
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@@ -2646,7 +2649,6 @@ x86_emulate(
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case 0xf8: /* fprem */
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case 0xf9: /* fyl2xp1 */
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case 0xfa: /* fsqrt */
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- case 0xfb: /* fsincos */
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case 0xfc: /* frndint */
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case 0xfd: /* fscale */
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case 0xfe: /* fsin */
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--- a/xen/include/asm-x86/amd.h
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+++ b/xen/include/asm-x86/amd.h
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@@ -138,6 +138,12 @@
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AMD_OSVW_ERRATUM(1, AMD_MODEL_RANGE(0xf, 0x41, 0x2, 0xff, 0xf), \
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AMD_MODEL_RANGE(0x10, 0x2, 0x1, 0xff, 0xf))
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+#define AMD_ERRATUM_573 \
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+ AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x0f, 0x0, 0x0, 0xff, 0xf), \
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+ AMD_MODEL_RANGE(0x10, 0x0, 0x0, 0xff, 0xf), \
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+ AMD_MODEL_RANGE(0x11, 0x0, 0x0, 0xff, 0xf), \
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+ AMD_MODEL_RANGE(0x12, 0x0, 0x0, 0xff, 0xf))
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+
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struct cpuinfo_x86;
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int cpu_has_amd_erratum(const struct cpuinfo_x86 *, int, ...);
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