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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
Show stats 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) {

2
hw/s390x/s390-virtio-ccw.c
View file

@ -330,7 +330,7 @@ static inline void s390_do_cpu_ipl(CPUState *cs, run_on_cpu_data arg)
static void s390_machine_unprotect(S390CcwMachineState *ms)
{
if (!s390_pv_vm_try_disable_async()) {
if (!s390_pv_vm_try_disable_async(ms)) {
s390_pv_vm_disable();
}
ms->pv = false;

6
include/hw/s390x/pv.h
View file

@ -14,10 +14,10 @@
#include "qapi/error.h"
#include "sysemu/kvm.h"
#include "hw/s390x/s390-virtio-ccw.h"
#ifdef CONFIG_KVM
#include "cpu.h"
#include "hw/s390x/s390-virtio-ccw.h"
static inline bool s390_is_pv(void)
{
@ -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);
@ -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) {}