From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Fri, 28 Jul 2023 17:42:12 +0000 (+0100)
Subject: x86/amd: Fix DE_CFG truncation in amd_check_zenbleed()
X-Git-Tag: RELEASE-4.14.6~60
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=602ee4c2954ed3f9f8552e08043146bee60ec012;p=xen.git

x86/amd: Fix DE_CFG truncation in amd_check_zenbleed()

This line:

	val &= ~chickenbit;

ends up truncating val to 32 bits, and turning off various errata workarounds
in Zen2 systems.

Fixes: f91c5ea97067 ("x86/amd: Mitigations for Zenbleed")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit c0dd53b8cbd1e47e9c89873a9265a7170bdc6b4c)
---

diff --git a/xen/arch/x86/cpu/amd.c b/xen/arch/x86/cpu/amd.c
index 9db79f409a..a1447f37ec 100644
--- a/xen/arch/x86/cpu/amd.c
+++ b/xen/arch/x86/cpu/amd.c
@@ -760,8 +760,8 @@ void amd_init_spectral_chicken(void)
 void amd_check_zenbleed(void)
 {
 	const struct cpu_signature *sig = &this_cpu(cpu_sig);
-	unsigned int good_rev, chickenbit = (1 << 9);
-	uint64_t val, old_val;
+	unsigned int good_rev;
+	uint64_t val, old_val, chickenbit = (1 << 9);
 
 	/*
 	 * If we're virtualised, we can't do family/model checks safely, and