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s390x/pv: Fix spurious warning with asynchronous teardown

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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>
Message-Id: <20230510105531.30623-2-imbrenda@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
[thuth: Fix inline function parameter in pv.h]
Signed-off-by: Thomas Huth <thuth@redhat.com>
This commit is contained in:
Claudio Imbrenda 2023-05-10 12:55:31 +02:00 • committed by Thomas Huth
parent 80bd81cadd
commit 88693ab2a5
3 changed files with 12 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

10
hw/s390x/pv.c
View file

@ -13,6 +13,7 @@
#include <linux/kvm.h>
#include "qemu/units.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "sysemu/kvm.h"
@ -115,7 +116,7 @@ static void *s390_pv_do_unprot_async_fn(void *p)
return NULL;
}
bool s390_pv_vm_try_disable_async(void)
bool s390_pv_vm_try_disable_async(S390CcwMachineState *ms)
{
/*
* t is only needed to create the thread; once qemu_thread_create
@ -123,7 +124,12 @@ bool s390_pv_vm_try_disable_async(void)
*/
QemuThread t;
if (!kvm_check_extension(kvm_state, KVM_CAP_S390_PROTECTED_ASYNC_DISABLE)) {
/*
* If the feature is not present or if the VM is not larger than 2 GiB,
* KVM_PV_ASYNC_CLEANUP_PREPARE fill fail; no point in attempting it.
*/
if ((MACHINE(ms)->maxram_size <= 2 * GiB) ||
!kvm_check_extension(kvm_state, KVM_CAP_S390_PROTECTED_ASYNC_DISABLE)) {
return false;
}
if (s390_pv_cmd(KVM_PV_ASYNC_CLEANUP_PREPARE, NULL) != 0) {