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 4ed08df4a8ce1399356cfcf197668b63bc04efd9..81008a2d94b2a3e84975ace48bd98d0257133def 100644 (file)
--- a/xen/arch/x86/cpu/amd.c
+++ b/xen/arch/x86/cpu/amd.c
@@ -773,8 +773,8 @@ void __init detect_zen2_null_seg_behaviour(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