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SUSE:SLE-12-SP2:GA
xen.7653
5afc13ae-4-x86-fold-XEN_IBRS-ALTERNATIVES.patch
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File 5afc13ae-4-x86-fold-XEN_IBRS-ALTERNATIVES.patch of Package xen.7653
# Commit af949407eaba7af71067f23d5866cd0bf1f1144d # Date 2018-05-16 12:19:10 +0100 # Author Andrew Cooper <andrew.cooper3@citrix.com> # Committer Andrew Cooper <andrew.cooper3@citrix.com> x86/spec_ctrl: Fold the XEN_IBRS_{SET,CLEAR} ALTERNATIVES together Currently, the SPEC_CTRL_{ENTRY,EXIT}_* macros encode Xen's choice of MSR_SPEC_CTRL as an immediate constant, and chooses between IBRS or not by doubling up the entire alternative block. There is now a variable holding Xen's choice of value, so use that and simplify the alternatives. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Wei Liu <wei.liu2@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> --- a/xen/arch/x86/cpu/common.c +++ b/xen/arch/x86/cpu/common.c @@ -357,13 +357,9 @@ void __cpuinit identify_cpu(struct cpuin if (test_bit(X86_FEATURE_IND_THUNK_JMP, boot_cpu_data.x86_capability)) __set_bit(X86_FEATURE_IND_THUNK_JMP, c->x86_capability); - if (test_bit(X86_FEATURE_XEN_IBRS_SET, + if (test_bit(X86_FEATURE_SC_MSR, boot_cpu_data.x86_capability)) - __set_bit(X86_FEATURE_XEN_IBRS_SET, c->x86_capability); - if (test_bit(X86_FEATURE_XEN_IBRS_CLEAR, - boot_cpu_data.x86_capability)) - __set_bit(X86_FEATURE_XEN_IBRS_CLEAR, - c->x86_capability); + __set_bit(X86_FEATURE_SC_MSR, c->x86_capability); if (test_bit(X86_FEATURE_RSB_NATIVE, boot_cpu_data.x86_capability)) __set_bit(X86_FEATURE_RSB_NATIVE, c->x86_capability); --- a/xen/arch/x86/spec_ctrl.c +++ b/xen/arch/x86/spec_ctrl.c @@ -114,8 +114,9 @@ static void __init print_details(enum in thunk == THUNK_RETPOLINE ? "RETPOLINE" : thunk == THUNK_LFENCE ? "LFENCE" : thunk == THUNK_JMP ? "JMP" : "?", - boot_cpu_has(X86_FEATURE_XEN_IBRS_SET) ? " IBRS+" : - boot_cpu_has(X86_FEATURE_XEN_IBRS_CLEAR) ? " IBRS-" : "", + boot_cpu_has(X86_FEATURE_SC_MSR) ? + default_xen_spec_ctrl & SPEC_CTRL_IBRS ? " IBRS+" : + " IBRS-" : "", opt_ibpb ? " IBPB" : "", boot_cpu_has(X86_FEATURE_RSB_NATIVE) ? " RSB_NATIVE" : "", boot_cpu_has(X86_FEATURE_RSB_VMEXIT) ? " RSB_VMEXIT" : ""); @@ -271,13 +272,10 @@ void __init init_speculation_mitigations * need the IBRS entry/exit logic to virtualise IBRS support for * guests. */ + __set_bit(X86_FEATURE_SC_MSR, boot_cpu_data.x86_capability); + if ( ibrs ) - { default_xen_spec_ctrl |= SPEC_CTRL_IBRS; - __set_bit(X86_FEATURE_XEN_IBRS_SET, boot_cpu_data.x86_capability); - } - else - __set_bit(X86_FEATURE_XEN_IBRS_CLEAR, boot_cpu_data.x86_capability); default_spec_ctrl_flags |= SCF_ist_wrmsr; } --- a/xen/include/asm-x86/cpufeature.h +++ b/xen/include/asm-x86/cpufeature.h @@ -67,8 +67,7 @@ #define X86_FEATURE_IND_THUNK_LFENCE (3*32+ 1) /* Use IND_THUNK_LFENCE */ #define X86_FEATURE_IND_THUNK_JMP (3*32+ 2) /* Use IND_THUNK_JMP */ #define X86_FEATURE_XEN_IBPB (3*32+ 3) /* IBRSB || IBPB */ -#define X86_FEATURE_XEN_IBRS_SET (3*32+ 4) /* IBRSB && IRBS set in Xen */ -#define X86_FEATURE_XEN_IBRS_CLEAR (3*32+ 5) /* IBRSB && IBRS clear in Xen */ +#define X86_FEATURE_SC_MSR (3*32+ 4) /* MSR_SPEC_CTRL used by Xen */ #define X86_FEATURE_MFENCE_RDTSC (3*32+ 7) /* MFENCE synchronizes RDTSC */ #define X86_FEATURE_CONSTANT_TSC (3*32+ 8) /* TSC ticks at a constant rate */ #define X86_FEATURE_NONSTOP_TSC (3*32+ 9) /* TSC does not stop in C states */ --- a/xen/include/asm-x86/nops.h +++ b/xen/include/asm-x86/nops.h @@ -61,11 +61,12 @@ #define ASM_NOP7 _ASM_MK_NOP(K8_NOP7) #define ASM_NOP8 _ASM_MK_NOP(K8_NOP8) -#define ASM_NOP22 ASM_NOP8; ASM_NOP8; ASM_NOP6 #define ASM_NOP23 ASM_NOP8; ASM_NOP8; ASM_NOP7 #define ASM_NOP24 ASM_NOP8; ASM_NOP8; ASM_NOP8 -#define ASM_NOP32 ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP8 -#define ASM_NOP36 ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP4 +#define ASM_NOP25 ASM_NOP8; ASM_NOP8; ASM_NOP7; ASM_NOP2 +#define ASM_NOP33 ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP7; ASM_NOP2 +#define ASM_NOP34 ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP2 +#define ASM_NOP39 ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP7 #define ASM_NOP40 ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP8; ASM_NOP8 #define ASM_NOP_MAX 8 --- a/xen/include/asm-x86/spec_ctrl.h +++ b/xen/include/asm-x86/spec_ctrl.h @@ -54,14 +54,16 @@ static always_inline void spec_ctrl_ente barrier(); info->spec_ctrl_flags |= SCF_use_shadow; barrier(); - asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", X86_FEATURE_XEN_IBRS_SET) - :: "a" (val), "c" (MSR_SPEC_CTRL), "d" (0) : "memory" ); + asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", %c3) + :: "a" (val), "c" (MSR_SPEC_CTRL), "d" (0), + "i" (X86_FEATURE_SC_MSR) + : "memory" ); } /* WARNING! `ret`, `call *`, `jmp *` not safe before this call. */ static always_inline void spec_ctrl_exit_idle(struct cpu_info *info) { - uint32_t val = SPEC_CTRL_IBRS; + uint32_t val = info->xen_spec_ctrl; /* * Disable shadowing before updating the MSR. There are no SMP issues @@ -69,8 +71,10 @@ static always_inline void spec_ctrl_exit */ info->spec_ctrl_flags &= ~SCF_use_shadow; barrier(); - asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", X86_FEATURE_XEN_IBRS_SET) - :: "a" (val), "c" (MSR_SPEC_CTRL), "d" (0) : "memory" ); + asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", %c3) + :: "a" (val), "c" (MSR_SPEC_CTRL), "d" (0), + "i" (X86_FEATURE_SC_MSR) + : "memory" ); } #endif /* !__X86_SPEC_CTRL_H__ */ --- a/xen/include/asm-x86/spec_ctrl_asm.h +++ b/xen/include/asm-x86/spec_ctrl_asm.h @@ -117,7 +117,7 @@ mov %\tmp, %rsp /* Restore old %rsp */ .endm -.macro DO_SPEC_CTRL_ENTRY_FROM_VMEXIT ibrs_val:req +.macro DO_SPEC_CTRL_ENTRY_FROM_VMEXIT /* * Requires %rbx=current, %rsp=regs/cpuinfo * Clobbers %rax, %rcx, %rdx @@ -137,11 +137,11 @@ andb $~SCF_use_shadow, CPUINFO_spec_ctrl_flags(%rsp) /* Load Xen's intended value. */ - mov $\ibrs_val, %eax + movzbl CPUINFO_xen_spec_ctrl(%rsp), %eax wrmsr .endm -.macro DO_SPEC_CTRL_ENTRY maybexen:req ibrs_val:req +.macro DO_SPEC_CTRL_ENTRY maybexen:req /* * Requires %rsp=regs (also cpuinfo if !maybexen) * Requires %r14=stack_end (if maybexen) @@ -166,12 +166,12 @@ setnz %al not %eax and %al, STACK_CPUINFO_FIELD(spec_ctrl_flags)(%r14) + movzbl STACK_CPUINFO_FIELD(xen_spec_ctrl)(%r14), %eax .else andb $~SCF_use_shadow, CPUINFO_spec_ctrl_flags(%rsp) + movzbl CPUINFO_xen_spec_ctrl(%rsp), %eax .endif - /* Load Xen's intended value. */ - mov $\ibrs_val, %eax wrmsr .endm @@ -219,47 +219,32 @@ #define SPEC_CTRL_ENTRY_FROM_VMEXIT \ ALTERNATIVE __stringify(ASM_NOP40), \ DO_OVERWRITE_RSB, X86_FEATURE_RSB_VMEXIT; \ - ALTERNATIVE_2 __stringify(ASM_NOP33), \ - __stringify(DO_SPEC_CTRL_ENTRY_FROM_VMEXIT \ - ibrs_val=SPEC_CTRL_IBRS), \ - X86_FEATURE_XEN_IBRS_SET, \ - __stringify(DO_SPEC_CTRL_ENTRY_FROM_VMEXIT \ - ibrs_val=0), \ - X86_FEATURE_XEN_IBRS_CLEAR + ALTERNATIVE __stringify(ASM_NOP34), \ + DO_SPEC_CTRL_ENTRY_FROM_VMEXIT, X86_FEATURE_SC_MSR /* Use after an entry from PV context (syscall/sysenter/int80/int82/etc). */ #define SPEC_CTRL_ENTRY_FROM_PV \ ALTERNATIVE __stringify(ASM_NOP40), \ DO_OVERWRITE_RSB, X86_FEATURE_RSB_NATIVE; \ - ALTERNATIVE_2 __stringify(ASM_NOP22), \ - __stringify(DO_SPEC_CTRL_ENTRY maybexen=0 \ - ibrs_val=SPEC_CTRL_IBRS), \ - X86_FEATURE_XEN_IBRS_SET, \ - __stringify(DO_SPEC_CTRL_ENTRY maybexen=0 ibrs_val=0), \ - X86_FEATURE_XEN_IBRS_CLEAR + ALTERNATIVE __stringify(ASM_NOP25), \ + __stringify(DO_SPEC_CTRL_ENTRY maybexen=0), X86_FEATURE_SC_MSR /* Use in interrupt/exception context. May interrupt Xen or PV context. */ #define SPEC_CTRL_ENTRY_FROM_INTR \ ALTERNATIVE __stringify(ASM_NOP40), \ DO_OVERWRITE_RSB, X86_FEATURE_RSB_NATIVE; \ - ALTERNATIVE_2 __stringify(ASM_NOP36), \ - __stringify(DO_SPEC_CTRL_ENTRY maybexen=1 \ - ibrs_val=SPEC_CTRL_IBRS), \ - X86_FEATURE_XEN_IBRS_SET, \ - __stringify(DO_SPEC_CTRL_ENTRY maybexen=1 ibrs_val=0), \ - X86_FEATURE_XEN_IBRS_CLEAR + ALTERNATIVE __stringify(ASM_NOP39), \ + __stringify(DO_SPEC_CTRL_ENTRY maybexen=1), X86_FEATURE_SC_MSR /* Use when exiting to Xen context. */ #define SPEC_CTRL_EXIT_TO_XEN \ - ALTERNATIVE_2 __stringify(ASM_NOP23), \ - DO_SPEC_CTRL_EXIT_TO_XEN, X86_FEATURE_XEN_IBRS_SET, \ - DO_SPEC_CTRL_EXIT_TO_XEN, X86_FEATURE_XEN_IBRS_CLEAR + ALTERNATIVE __stringify(ASM_NOP23), \ + DO_SPEC_CTRL_EXIT_TO_XEN, X86_FEATURE_SC_MSR /* Use when exiting to guest context. */ #define SPEC_CTRL_EXIT_TO_GUEST \ - ALTERNATIVE_2 __stringify(ASM_NOP24), \ - DO_SPEC_CTRL_EXIT_TO_GUEST, X86_FEATURE_XEN_IBRS_SET, \ - DO_SPEC_CTRL_EXIT_TO_GUEST, X86_FEATURE_XEN_IBRS_CLEAR + ALTERNATIVE __stringify(ASM_NOP24), \ + DO_SPEC_CTRL_EXIT_TO_GUEST, X86_FEATURE_SC_MSR /* TODO: Drop these when the alternatives infrastructure is NMI/#MC safe. */ .macro SPEC_CTRL_ENTRY_FROM_INTR_IST
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