[xen stable-4.16] xen/arm: move errata CSV2 check earlier

[patchbot@xxxxxxx]

commit 3d963874461b3001e33f3ff90e285670f04d16c4
Author:     Bertrand Marquis <bertrand.marquis@xxxxxxx>
AuthorDate: Tue Feb 15 10:39:47 2022 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Mar 8 17:15:41 2022 +0000

    xen/arm: move errata CSV2 check earlier
    
    CSV2 availability check is done after printing to the user that
    workaround 1 will be used. Move the check before to prevent saying to the
    user that workaround 1 is used when it is not because it is not needed.
    This will also allow to reuse install_bp_hardening_vec function for
    other use cases.
    
    Code previously returning "true", now returns "0" to conform to
    enable_smccc_arch_workaround_1 returning an int and surrounding code
    doing a "return 0" if workaround is not needed.
    
    This is part of XSA-398 / CVE-2022-23960.
    
    Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
    Reviewed-by: Julien Grall <julien@xxxxxxx>
    (cherry picked from commit 599616d70eb886b9ad0ef9d6b51693ce790504ba)
---
 xen/arch/arm/cpuerrata.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/cpuerrata.c b/xen/arch/arm/cpuerrata.c
index b398d480f1..00f9ebe9ce 100644
--- a/xen/arch/arm/cpuerrata.c
+++ b/xen/arch/arm/cpuerrata.c
@@ -103,13 +103,6 @@ install_bp_hardening_vec(const struct arm_cpu_capabilities 
*entry,
     printk(XENLOG_INFO "CPU%u will %s on exception entry\n",
            smp_processor_id(), desc);
 
-    /*
-     * No need to install hardened vector when the processor has
-     * ID_AA64PRF0_EL1.CSV2 set.
-     */
-    if ( cpu_data[smp_processor_id()].pfr64.csv2 )
-        return true;
-
     spin_lock(&bp_lock);
 
     /*
@@ -167,6 +160,13 @@ static int enable_smccc_arch_workaround_1(void *data)
     if ( !entry->matches(entry) )
         return 0;
 
+    /*
+     * No need to install hardened vector when the processor has
+     * ID_AA64PRF0_EL1.CSV2 set.
+     */
+    if ( cpu_data[smp_processor_id()].pfr64.csv2 )
+        return 0;
+
     if ( smccc_ver < SMCCC_VERSION(1, 1) )
         goto warn;
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.16