The MSRs used by setup_k7_watchdog() are architectural in 64bit.  The Unit
Select (0x76, cycles not in halt state) isn't, but it hasn't changed in 23
years, making this a trend likely to continue.

Drop the family check.  If the Unit Select does happen to change meaning in
the future, check_nmi_watchdog() will still notice the watchdog not operating
as expected.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
---
 xen/arch/x86/nmi.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/xen/arch/x86/nmi.c b/xen/arch/x86/nmi.c
index 33f77a92047f..f6329cb0270e 100644
--- a/xen/arch/x86/nmi.c
+++ b/xen/arch/x86/nmi.c
@@ -387,15 +387,12 @@ void setup_apic_nmi_watchdog(void)
     if ( nmi_watchdog == NMI_NONE )
         return;
 
-    switch (boot_cpu_data.x86_vendor) {
+    switch ( boot_cpu_data.x86_vendor )
+    {
     case X86_VENDOR_AMD:
-        switch (boot_cpu_data.x86) {
-        case 6:
-        case 0xf ... 0x19:
-            setup_k7_watchdog();
-            break;
-        }
+        setup_k7_watchdog();
         break;
+
     case X86_VENDOR_INTEL:
         switch (boot_cpu_data.x86) {
         case 6:
-- 
2.30.2

On 19.03.2024 15:48, Andrew Cooper wrote:
> The MSRs used by setup_k7_watchdog() are architectural in 64bit.  The Unit
> Select (0x76, cycles not in halt state) isn't, but it hasn't changed in 23
> years, making this a trend likely to continue.
> 
> Drop the family check.  If the Unit Select does happen to change meaning in
> the future, check_nmi_watchdog() will still notice the watchdog not operating
> as expected.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>

> --- a/xen/arch/x86/nmi.c
> +++ b/xen/arch/x86/nmi.c
> @@ -387,15 +387,12 @@ void setup_apic_nmi_watchdog(void)
>      if ( nmi_watchdog == NMI_NONE )
>          return;
>  
> -    switch (boot_cpu_data.x86_vendor) {
> +    switch ( boot_cpu_data.x86_vendor )
> +    {
>      case X86_VENDOR_AMD:
> -        switch (boot_cpu_data.x86) {
> -        case 6:

Just to mention it - this case label has been dead code anyway for about 10
years.

Jan

On 19/03/2024 4:51 pm, Jan Beulich wrote:
> On 19.03.2024 15:48, Andrew Cooper wrote:
>> The MSRs used by setup_k7_watchdog() are architectural in 64bit.  The Unit
>> Select (0x76, cycles not in halt state) isn't, but it hasn't changed in 23
>> years, making this a trend likely to continue.
>>
>> Drop the family check.  If the Unit Select does happen to change meaning in
>> the future, check_nmi_watchdog() will still notice the watchdog not operating
>> as expected.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>

Thanks.

>
>> --- a/xen/arch/x86/nmi.c
>> +++ b/xen/arch/x86/nmi.c
>> @@ -387,15 +387,12 @@ void setup_apic_nmi_watchdog(void)
>>      if ( nmi_watchdog == NMI_NONE )
>>          return;
>>  
>> -    switch (boot_cpu_data.x86_vendor) {
>> +    switch ( boot_cpu_data.x86_vendor )
>> +    {
>>      case X86_VENDOR_AMD:
>> -        switch (boot_cpu_data.x86) {
>> -        case 6:
> Just to mention it - this case label has been dead code anyway for about 10
> years.

Yeah... I noticed that after writing the commit message, although it's
not very easy to slip in.

Also it's 25 years since the K7 was released (June 1999), because I
apparently can't count.

~Andrew