[xen stable-4.17] x86/amd: Fix DE_CFG truncation in amd_check_zenbleed()

[patchbot@xxxxxxx]

commit c18b2dd93f396eadd116d0016cf7285523a13505
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Fri Jul 28 18:42:12 2023 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Mon Jul 31 13:55:09 2023 +0100

    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@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    (cherry picked from commit c0dd53b8cbd1e47e9c89873a9265a7170bdc6b4c)
---
 xen/arch/x86/cpu/amd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/cpu/amd.c b/xen/arch/x86/cpu/amd.c
index 8d23a5be0c..c452592872 100644
--- a/xen/arch/x86/cpu/amd.c
+++ b/xen/arch/x86/cpu/amd.c
@@ -882,8 +882,8 @@ 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
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.17