From: Andrew Cooper <andrew.cooper3@citrix.com>

Subject: 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>

diff --git a/xen/arch/x86/cpu/amd.c b/xen/arch/x86/cpu/amd.c

index 3ed06f670491..df2681b7c455 100644

--- a/xen/arch/x86/cpu/amd.c

+++ b/xen/arch/x86/cpu/amd.c

@@ -909,8 +909,8 @@ 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