diff options
Diffstat (limited to 'sys/amd64/amd64/initcpu.c')
| -rw-r--r-- | sys/amd64/amd64/initcpu.c | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/sys/amd64/amd64/initcpu.c b/sys/amd64/amd64/initcpu.c index 63c0f20f4928..ff3b6be8602e 100644 --- a/sys/amd64/amd64/initcpu.c +++ b/sys/amd64/amd64/initcpu.c @@ -48,6 +48,11 @@ __FBSDID("$FreeBSD$"); static int hw_instruction_sse; SYSCTL_INT(_hw, OID_AUTO, instruction_sse, CTLFLAG_RD, &hw_instruction_sse, 0, "SIMD/MMX2 instructions available in CPU"); +static int lower_sharedpage_init; +int hw_lower_amd64_sharedpage; +SYSCTL_INT(_hw, OID_AUTO, lower_amd64_sharedpage, CTLFLAG_RDTUN, + &hw_lower_amd64_sharedpage, 0, + "Lower sharedpage to work around Ryzen issue with executing code near the top of user memory"); /* * -1: automatic (default) * 0: keep enable CLFLUSH @@ -122,6 +127,28 @@ init_amd(void) wrmsr(0xc0011020, msr); } } + + /* + * Work around a problem on Ryzen that is triggered by executing + * code near the top of user memory, in our case the signal + * trampoline code in the shared page on amd64. + * + * This function is executed once for the BSP before tunables take + * effect so the value determined here can be overridden by the + * tunable. This function is then executed again for each AP and + * also on resume. Set a flag the first time so that value set by + * the tunable is not overwritten. + * + * The stepping and/or microcode versions should be checked after + * this issue is fixed by AMD so that we don't use this mode if not + * needed. + */ + if (lower_sharedpage_init == 0) { + lower_sharedpage_init = 1; + if (CPUID_TO_FAMILY(cpu_id) == 0x17) { + hw_lower_amd64_sharedpage = 1; + } + } } /* |