2037                 hdl = cmi_hdl_lookup(CMI_HDL_NATIVE, cmi_ntv_hwchipid(cp),
2038                     cmi_ntv_hwcoreid(cp), cmi_ntv_hwstrandid(cp));
2039         }
2040         if (hdl != NULL) {
2041                 cmi_faulted_exit(hdl);
2042                 cmi_hdl_rele(hdl);
2043         }
2044 #endif
2045 }
2046 
2047 /*
2048  * The following two routines are used as context operators on threads belonging
2049  * to processes with a private LDT (see sysi86).  Due to the rarity of such
2050  * processes, these routines are currently written for best code readability and
2051  * organization rather than speed.  We could avoid checking x86_featureset at
2052  * every context switch by installing different context ops, depending on
2053  * x86_featureset, at LDT creation time -- one for each combination of fast
2054  * syscall features.
2055  */
2056 
2057 /*ARGSUSED*/
2058 void
2059 cpu_fast_syscall_disable(void *arg)
2060 {
2061         if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
2062             is_x86_feature(x86_featureset, X86FSET_SEP))
2063                 cpu_sep_disable();
2064         if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
2065             is_x86_feature(x86_featureset, X86FSET_ASYSC))
2066                 cpu_asysc_disable();
2067 }
2068 
2069 /*ARGSUSED*/
2070 void
2071 cpu_fast_syscall_enable(void *arg)
2072 {
2073         if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
2074             is_x86_feature(x86_featureset, X86FSET_SEP))
2075                 cpu_sep_enable();
2076         if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
2077             is_x86_feature(x86_featureset, X86FSET_ASYSC))
2078                 cpu_asysc_enable();
2079 }
2080 
2081 static void
2082 cpu_sep_enable(void)
2083 {
2084         ASSERT(is_x86_feature(x86_featureset, X86FSET_SEP));
2085         ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);
2086 
2087         wrmsr(MSR_INTC_SEP_CS, (uint64_t)(uintptr_t)KCS_SEL);
2088 }
2089 
2090 static void
2091 cpu_sep_disable(void)

2037                 hdl = cmi_hdl_lookup(CMI_HDL_NATIVE, cmi_ntv_hwchipid(cp),
2038                     cmi_ntv_hwcoreid(cp), cmi_ntv_hwstrandid(cp));
2039         }
2040         if (hdl != NULL) {
2041                 cmi_faulted_exit(hdl);
2042                 cmi_hdl_rele(hdl);
2043         }
2044 #endif
2045 }
2046 
2047 /*
2048  * The following two routines are used as context operators on threads belonging
2049  * to processes with a private LDT (see sysi86).  Due to the rarity of such
2050  * processes, these routines are currently written for best code readability and
2051  * organization rather than speed.  We could avoid checking x86_featureset at
2052  * every context switch by installing different context ops, depending on
2053  * x86_featureset, at LDT creation time -- one for each combination of fast
2054  * syscall features.
2055  */
2056 

2057 void
2058 cpu_fast_syscall_disable(void)
2059 {
2060         if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
2061             is_x86_feature(x86_featureset, X86FSET_SEP))
2062                 cpu_sep_disable();
2063         if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
2064             is_x86_feature(x86_featureset, X86FSET_ASYSC))
2065                 cpu_asysc_disable();
2066 }
2067 

2068 void
2069 cpu_fast_syscall_enable(void)
2070 {
2071         if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
2072             is_x86_feature(x86_featureset, X86FSET_SEP))
2073                 cpu_sep_enable();
2074         if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
2075             is_x86_feature(x86_featureset, X86FSET_ASYSC))
2076                 cpu_asysc_enable();
2077 }
2078 
2079 static void
2080 cpu_sep_enable(void)
2081 {
2082         ASSERT(is_x86_feature(x86_featureset, X86FSET_SEP));
2083         ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);
2084 
2085         wrmsr(MSR_INTC_SEP_CS, (uint64_t)(uintptr_t)KCS_SEL);
2086 }
2087 
2088 static void
2089 cpu_sep_disable(void)