diff options
| author | Konstantin Belousov <kib@FreeBSD.org> | 2026-02-04 00:24:58 +0000 |
|---|---|---|
| committer | Konstantin Belousov <kib@FreeBSD.org> | 2026-02-13 07:55:04 +0000 |
| commit | 36ceb5509d01ff2e6482a78ca809c344574e9a25 (patch) | |
| tree | 2a6786d9ee0299e3b5626e8720f6f70ffa8a14f7 | |
| parent | af99e40af1dd4e8b39ca986240ee8b9aea722958 (diff) | |
x86_msr_op(9): consistently return the value read from MSR
If the operation is executed on more than one CPU, a random instance of
the read value is returned.
Reviewed by: markj, olce
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D55045
| -rw-r--r-- | sys/x86/x86/cpu_machdep.c | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/sys/x86/x86/cpu_machdep.c b/sys/x86/x86/cpu_machdep.c index 023b02ba7c76..6c3f4add6202 100644 --- a/sys/x86/x86/cpu_machdep.c +++ b/sys/x86/x86/cpu_machdep.c @@ -136,6 +136,8 @@ x86_msr_op_one_safe(struct msr_op_arg *a) atomic_cmpset_int(&a->error, 0, error); break; } + if (a->res != NULL) + atomic_store_64(a->res, v); v &= ~a->arg1; error = wrmsr_safe(a->msr, v); if (error != 0) @@ -147,6 +149,8 @@ x86_msr_op_one_safe(struct msr_op_arg *a) atomic_cmpset_int(&a->error, 0, error); break; } + if (a->res != NULL) + atomic_store_64(a->res, v); v |= a->arg1; error = wrmsr_safe(a->msr, v); if (error != 0) @@ -159,10 +163,12 @@ x86_msr_op_one_safe(struct msr_op_arg *a) break; case MSR_OP_READ: error = rdmsr_safe(a->msr, &v); - if (error == 0) - *a->res = v; - else + if (error == 0) { + if (a->res != NULL) + atomic_store_64(a->res, v); + } else { atomic_cmpset_int(&a->error, 0, error); + } break; } } @@ -175,11 +181,15 @@ x86_msr_op_one_unsafe(struct msr_op_arg *a) switch (a->op) { case MSR_OP_ANDNOT: v = rdmsr(a->msr); + if (a->res != NULL) + atomic_store_64(a->res, v); v &= ~a->arg1; wrmsr(a->msr, v); break; case MSR_OP_OR: v = rdmsr(a->msr); + if (a->res != NULL) + atomic_store_64(a->res, v); v |= a->arg1; wrmsr(a->msr, v); break; @@ -188,7 +198,8 @@ x86_msr_op_one_unsafe(struct msr_op_arg *a) break; case MSR_OP_READ: v = rdmsr(a->msr); - *a->res = v; + if (a->res != NULL) + atomic_store_64(a->res, v); break; default: __assert_unreachable(); |