File xsa439-8.patch of Package xen.31427
# Commit de1d265001397f308c5c3c5d3ffc30e7ef8c0705
# Date 2023-09-18 16:43:01 +0100
# Author Andrew Cooper <andrew.cooper3@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86/amd: Introduce is_zen{1,2}_uarch() predicates
We already have 3 cases using STIBP as a Zen1/2 heuristic, and are about to
introduce a 4th. Wrap the heuristic into a pair of predicates rather than
opencoding it, and the explanation of the heuristic, at each usage site.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/arch/x86/cpu/amd.c
+++ b/xen/arch/x86/cpu/amd.c
@@ -742,15 +742,13 @@ void amd_init_ssbd(const struct cpuinfo_
* non-branch instructions to be ignored. It is to be set unilaterally in
* newer microcode.
*
- * This chickenbit is something unrelated on Zen1, and Zen1 vs Zen2 isn't a
- * simple model number comparison, so use STIBP as a heuristic to separate the
- * two uarches in Fam17h(AMD)/18h(Hygon).
+ * This chickenbit is something unrelated on Zen1.
*/
void amd_init_spectral_chicken(void)
{
uint64_t val, chickenbit = 1 << 1;
- if (cpu_has_hypervisor || !boot_cpu_has(X86_FEATURE_AMD_STIBP))
+ if (cpu_has_hypervisor || !is_zen2_uarch())
return;
if (rdmsr_safe(MSR_AMD64_DE_CFG2, val) == 0 && !(val & chickenbit))
@@ -786,11 +784,8 @@ void amd_check_zenbleed(void)
* With the Fam17h check above, most parts getting here are
* Zen1. They're not affected. Assume Zen2 ones making it
* here are affected regardless of microcode version.
- *
- * Zen1 vs Zen2 isn't a simple model number comparison, so use
- * STIBP as a heuristic to distinguish.
*/
- if (!boot_cpu_has(X86_FEATURE_AMD_STIBP))
+ if (is_zen1_uarch())
return;
good_rev = ~0U;
break;
--- a/xen/include/asm-x86/amd.h
+++ b/xen/include/asm-x86/amd.h
@@ -140,6 +140,17 @@
AMD_MODEL_RANGE(0x11, 0x0, 0x0, 0xff, 0xf), \
AMD_MODEL_RANGE(0x12, 0x0, 0x0, 0xff, 0xf))
+/*
+ * The Zen1 and Zen2 microarchitectures are implemented by AMD (Fam17h) and
+ * Hygon (Fam18h) but without simple model number rules. Instead, use STIBP
+ * as a heuristic that distinguishes the two.
+ *
+ * The caller is required to perform the appropriate vendor/family checks
+ * first.
+ */
+#define is_zen1_uarch() (!boot_cpu_has(X86_FEATURE_AMD_STIBP))
+#define is_zen2_uarch() boot_cpu_has(X86_FEATURE_AMD_STIBP)
+
struct cpuinfo_x86;
int cpu_has_amd_erratum(const struct cpuinfo_x86 *, int, ...);