File xsa471-15.patch of Package xen.39862

# Commit 7c5025394dafe4b788ff9e1afc688f6becab9300
# Date 2025-07-08 15:08:08 +0100
# Author Andrew Cooper <andrew.cooper3@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86/cpu-policy: Rearrange guest_common_*_feature_adjustments()

Turn the if()s into switch()es, as we're going to need AMD sections.

Move the RTM adjustments into the Intel section, where they ought to live.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/cpu-policy.c
+++ b/xen/arch/x86/cpu-policy.c
@@ -420,8 +420,9 @@ static void __init guest_common_feature_
     if ( host_cpu_policy.feat.ibrsb )
         __set_bit(X86_FEATURE_IBPB, fs);
 
-    if ( boot_cpu_data.x86_vendor == X86_VENDOR_INTEL )
+    switch ( boot_cpu_data.x86_vendor )
     {
+    case X86_VENDOR_INTEL:
         /*
          * These bits indicate that the VERW instruction may have gained
          * scrubbing side effects.  With pooling, they mean "you might migrate
@@ -432,22 +433,23 @@ static void __init guest_common_feature_
         __set_bit(X86_FEATURE_MD_CLEAR, fs);
         __set_bit(X86_FEATURE_FB_CLEAR, fs);
         __set_bit(X86_FEATURE_RFDS_CLEAR, fs);
-    }
 
-    /*
-     * To mitigate Native-BHI, one option is to use a TSX Abort on capable
-     * systems.  This is safe even if RTM has been disabled for other reasons
-     * via MSR_TSX_{CTRL,FORCE_ABORT}.  However, a guest kernel doesn't get to
-     * know this type of information.
-     *
-     * Therefore the meaning of RTM_ALWAYS_ABORT has been adjusted, to instead
-     * mean "XBEGIN won't fault".  This is enough for a guest kernel to make
-     * an informed choice WRT mitigating Native-BHI.
-     *
-     * If RTM-capable, we can run a VM which has seen RTM_ALWAYS_ABORT.
-     */
-    if ( test_bit(X86_FEATURE_RTM, fs) )
-        __set_bit(X86_FEATURE_RTM_ALWAYS_ABORT, fs);
+        /*
+         * To mitigate Native-BHI, one option is to use a TSX Abort on capable
+         * systems.  This is safe even if RTM has been disabled for other
+         * reasons via MSR_TSX_{CTRL,FORCE_ABORT}.  However, a guest kernel
+         * doesn't get to know this type of information.
+         *
+         * Therefore the meaning of RTM_ALWAYS_ABORT has been adjusted, to
+         * instead mean "XBEGIN won't fault".  This is enough for a guest
+         * kernel to make an informed choice WRT mitigating Native-BHI.
+         *
+         * If RTM-capable, we can run a VM which has seen RTM_ALWAYS_ABORT.
+         */
+        if ( test_bit(X86_FEATURE_RTM, fs) )
+            __set_bit(X86_FEATURE_RTM_ALWAYS_ABORT, fs);
+        break;
+    }
 }
 
 static void __init calculate_pv_max_policy(void)