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SUSE:SLE-12-SP4:Update
xen.11298
xsa297-0c.patch
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File xsa297-0c.patch of Package xen.11298
x86/spec-ctrl: Misc non-functional cleanup * Identify BTI in the spec_ctrl_{enter,exit}_idle() comments, as other mitigations will shortly appear. * Use alternative_input() and cover the lack of memory cobber with a further barrier. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> --- a/xen/include/asm-x86/spec_ctrl.h +++ b/xen/include/asm-x86/spec_ctrl.h @@ -65,6 +65,8 @@ static always_inline void spec_ctrl_ente uint32_t val = 0; /* + * Branch Target Injection: + * * Latch the new shadow value, then enable shadowing, then update the MSR. * There are no SMP issues here; only local processor ordering concerns. */ @@ -72,10 +74,10 @@ static always_inline void spec_ctrl_ente barrier(); info->spec_ctrl_flags |= SCF_use_shadow; barrier(); - asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", %c3) - :: "a" (val), "c" (MSR_SPEC_CTRL), "d" (0), - "i" (X86_FEATURE_SC_MSR_IDLE) - : "memory" ); + alternative_input(ASM_NOP3, "wrmsr", %c3, + "a" (val), "c" (MSR_SPEC_CTRL), "d" (0), + "i" (X86_FEATURE_SC_MSR_IDLE)); + barrier(); } /* WARNING! `ret`, `call *`, `jmp *` not safe before this call. */ @@ -84,15 +86,17 @@ static always_inline void spec_ctrl_exit uint32_t val = info->xen_spec_ctrl; /* + * Branch Target Injection: + * * Disable shadowing before updating the MSR. There are no SMP issues * here; only local processor ordering concerns. */ info->spec_ctrl_flags &= ~SCF_use_shadow; barrier(); - asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", %c3) - :: "a" (val), "c" (MSR_SPEC_CTRL), "d" (0), - "i" (X86_FEATURE_SC_MSR_IDLE) - : "memory" ); + alternative_input(ASM_NOP3, "wrmsr", %c3, + "a" (val), "c" (MSR_SPEC_CTRL), "d" (0), + "i" (X86_FEATURE_SC_MSR_IDLE)); + barrier(); } #endif /* !__X86_SPEC_CTRL_H__ */ --- a/xen/include/asm-x86/alternative.h +++ b/xen/include/asm-x86/alternative.h @@ -5,6 +5,7 @@ #include <asm/nops.h> #ifndef __ASSEMBLY__ +#include <xen/stringify.h> #include <xen/types.h> struct alt_instr { @@ -66,6 +67,25 @@ extern void alternative_instructions(voi #define alternative(oldinstr, newinstr, feature) \ asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory") +/* + * Alternative inline assembly with input. + * + * Pecularities: + * No memory clobber here. + * Argument numbers start with 1. + * Best is to use constraints that are fixed size (like (%1) ... "r") + * If you use variable sized constraints like "m" or "g" in the + * replacement make sure to pad to the worst case length. + */ +#define alternative_input(oldinstr, newinstr, feature, input...) \ + asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \ + : : input) + +/* Like alternative_input, but with a single output argument */ +#define alternative_io(oldinstr, newinstr, feature, output, input...) \ + asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \ + : output : input) + #endif /* !__ASSEMBLY__ */ #endif /* __X86_ALTERNATIVE_H__ */
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