Re: [PATCH v2 1/1] s390x/pv: Fix spurious warning with asynchronous teardown

[Thomas Huth <thuth@redhat.com>]

On 10/05/2023 12.55, Claudio Imbrenda wrote:
> Kernel commit 292a7d6fca33 ("KVM: s390: pv: fix asynchronous teardown
> for small VMs") causes the KVM_PV_ASYNC_CLEANUP_PREPARE ioctl to fail
> if the VM is not larger than 2GiB. QEMU would attempt it and fail,
> print an error message, and then proceed with a normal teardown.
> 
> Avoid attempting to use asynchronous teardown altogether when the VM is
> not larger than 2 GiB. This will avoid triggering the error message and
> also avoid pointless overhead; normal teardown is fast enough for small
> VMs.
> 
> Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
> Fixes: c3a073c610 ("s390x/pv: Add support for asynchronous teardown for reboot")
> Link: https://lore.kernel.org/all/20230421085036.52511-2-imbrenda@linux.ibm.com/
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
...
> diff --git a/include/hw/s390x/pv.h b/include/hw/s390x/pv.h
> index 966306a9db..6766557fb7 100644
> --- a/include/hw/s390x/pv.h
> +++ b/include/hw/s390x/pv.h
> @@ -41,7 +41,7 @@ static inline bool s390_is_pv(void)
>   int s390_pv_query_info(void);
>   int s390_pv_vm_enable(void);
>   void s390_pv_vm_disable(void);
> -bool s390_pv_vm_try_disable_async(void);
> +bool s390_pv_vm_try_disable_async(S390CcwMachineState *ms);
>   int s390_pv_set_sec_parms(uint64_t origin, uint64_t length);
>   int s390_pv_unpack(uint64_t addr, uint64_t size, uint64_t tweak);
>   void s390_pv_prep_reset(void);

I'll squash this on top to fix a build failure on non-s390x host systems:

diff --git a/include/hw/s390x/pv.h b/include/hw/s390x/pv.h
--- a/include/hw/s390x/pv.h
+++ b/include/hw/s390x/pv.h
@@ -61,7 +61,7 @@ static inline bool s390_is_pv(void) { return false; }
  static inline int s390_pv_query_info(void) { return 0; }
  static inline int s390_pv_vm_enable(void) { return 0; }
  static inline void s390_pv_vm_disable(void) {}
-static inline bool s390_pv_vm_try_disable_async(void) { return false; }
+static inline bool s390_pv_vm_try_disable_async(S390CcwMachineState *ms) { return false; }
  static inline int s390_pv_set_sec_parms(uint64_t origin, uint64_t length) { return 0; }
  static inline int s390_pv_unpack(uint64_t addr, uint64_t size, uint64_t tweak) { return 0; }
  static inline void s390_pv_prep_reset(void) {}

  Thomas