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qemu-kvm/SOURCES/kvm-s390x-pv-Fix-spurious-w...

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From 3cab2a638a10ece2b76d9f33a3c5dc6f64f1bbaa Mon Sep 17 00:00:00 2001
From: Claudio Imbrenda <imbrenda@linux.ibm.com>
Date: Wed, 10 May 2023 12:55:31 +0200
Subject: [PATCH 21/21] s390x/pv: Fix spurious warning with asynchronous
teardown
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
RH-Author: Thomas Huth <thuth@redhat.com>
RH-MergeRequest: 173: Improve memory reclaiming for z15 Secure Execution guests
RH-Bugzilla: 2168500
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Cédric Le Goater <clg@redhat.com>
RH-Commit: [2/2] cb690d3155ea22c6df00a4d75b72f501515e5556 (thuth/qemu-kvm-cs9)
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2168500
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>
(cherry picked from commit 88693ab2a53f2f3d25cb39a7b5034ab391bc5a81)
---
hw/s390x/pv.c | 10 ++++++++--
hw/s390x/s390-virtio-ccw.c | 2 +-
include/hw/s390x/pv.h | 6 +++---
3 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/hw/s390x/pv.c b/hw/s390x/pv.c
index 49ea38236c..b63f3784c6 100644
--- a/hw/s390x/pv.c
+++ b/hw/s390x/pv.c
@@ -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) {
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 6a0b93c63d..d95c595f88 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -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;
diff --git a/include/hw/s390x/pv.h b/include/hw/s390x/pv.h
index 966306a9db..7b935e2246 100644
--- a/include/hw/s390x/pv.h
+++ b/include/hw/s390x/pv.h
@@ -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) {}
--
2.39.3