[xen staging] xen/arm64: Hide FEAT_SME

[patchbot@xxxxxxx]

commit 98060fc4a31ff56f1375446b21dc4b52836e22bd
Author:     Julien Grall <julien@xxxxxxx>
AuthorDate: Wed Aug 14 22:00:54 2024 +0100
Commit:     Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Thu Aug 22 11:09:42 2024 +0100

    xen/arm64: Hide FEAT_SME
    
    Newer hardware may support FEAT_SME. Xen doesn't have any knowledge but
    it will still expose the feature to the VM. If the OS is trying to use
    SME, then it will crash.
    
    Solve by hiding FEAT_SME.
    
    Signed-off-by: Julien Grall <julien@xxxxxxx>
    Acked-by: Michal Orzel <michal.orzel@xxxxxxx>
    Reviewed-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
---
 xen/arch/arm/cpufeature.c             | 3 +++
 xen/arch/arm/include/asm/cpufeature.h | 4 +++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/cpufeature.c b/xen/arch/arm/cpufeature.c
index ef77473bf8..b45dbe3c66 100644
--- a/xen/arch/arm/cpufeature.c
+++ b/xen/arch/arm/cpufeature.c
@@ -208,6 +208,9 @@ static int __init create_domain_cpuinfo(void)
     domain_cpuinfo.pfr64.sve = 0;
     domain_cpuinfo.zfr64.bits[0] = 0;
 
+    /* Hide SMT support as Xen does not support it */
+    domain_cpuinfo.pfr64.sme = 0;
+
     /* Hide MTE support as Xen does not support it */
     domain_cpuinfo.pfr64.mte = 0;
 
diff --git a/xen/arch/arm/include/asm/cpufeature.h 
b/xen/arch/arm/include/asm/cpufeature.h
index c95582044a..969e043f5b 100644
--- a/xen/arch/arm/include/asm/cpufeature.h
+++ b/xen/arch/arm/include/asm/cpufeature.h
@@ -207,7 +207,9 @@ struct cpuinfo_arm {
             unsigned long mte:4;
             unsigned long ras_frac:4;
             unsigned long mpam_frac:4;
-            unsigned long __res1:44;
+            unsigned long __res1:4;
+            unsigned long sme:4;
+            unsigned long __res2:36;
         };
     } pfr64;
 
--
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