Re: [PATCH] target/i386/monitor: synchronize cpu before printing lapic state

[Dongli Zhang]

Hi David,

On 10/26/23 08:39, David Woodhouse wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
> 
> Where the local APIC is emulated by KVM, we need kvm_get_apic() to pull
> the current state into userspace before it's printed. Otherwise we get
> stale values.
> 
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
>  target/i386/monitor.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/target/i386/monitor.c b/target/i386/monitor.c
> index 6512846327..0754d699ba 100644
> --- a/target/i386/monitor.c
> +++ b/target/i386/monitor.c
> @@ -29,6 +29,7 @@
>  #include "monitor/hmp.h"
>  #include "qapi/qmp/qdict.h"
>  #include "sysemu/kvm.h"
> +#include "sysemu/hw_accel.h"
>  #include "qapi/error.h"
>  #include "qapi/qapi-commands-misc-target.h"
>  #include "qapi/qapi-commands-misc.h"
> @@ -655,6 +656,7 @@ void hmp_info_local_apic(Monitor *mon, const QDict *qdict)
>      if (qdict_haskey(qdict, "apic-id")) {
>          int id = qdict_get_try_int(qdict, "apic-id", 0);
>          cs = cpu_by_arch_id(id);
> +        cpu_synchronize_state(cs);

AFAIR, there is a case that cs may be NULL here when I was sending the similar
bugfix long time ago.

https://lore.kernel.org/qemu-devel/20210701214051.1588-1-dongli.zhang@oracle.com/

... and resend:

https://lore.kernel.org/qemu-devel/20210908143803.29191-1-dongli.zhang@oracle.com/

... and resent by Daniel as part of another patchset (after review):

https://lore.kernel.org/qemu-devel/20211028155457.967291-19-berrange@redhat.com/


This utility is helpful for the diagnostic of loss of interrupt issue.

Dongli Zhang

>      } else {
>          cs = mon_get_cpu(mon);
>      }