* [PATCH v4 1/4] x86/kvm: Add "nopvspin" parameter to disable PV spinlocks
2019-10-03 14:02 [PATCH v4 0/4] Add a unified parameter "nopvspin" Zhenzhong Duan
@ 2019-10-03 14:02 ` Zhenzhong Duan
2019-10-04 14:52 ` Boris Ostrovsky
2019-10-03 14:02 ` [PATCH v4 2/4] x86/kvm: Change print code to use pr_*() format Zhenzhong Duan
` (2 subsequent siblings)
3 siblings, 1 reply; 12+ messages in thread
From: Zhenzhong Duan @ 2019-10-03 14:02 UTC (permalink / raw)
To: linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, boris.ostrovsky, jgross, sstabellini,
peterz, Zhenzhong Duan, Jonathan Corbet, H. Peter Anvin,
Will Deacon
There are cases where a guest tries to switch spinlocks to bare metal
behavior (e.g. by setting "xen_nopvspin" on XEN platform and
"hv_nopvspin" on HYPER_V).
That feature is missed on KVM, add a new parameter "nopvspin" to disable
PV spinlocks for KVM guest.
The new 'nopvspin' parameter will also replace Xen and Hyper-V specific
parameters in future patches.
Define variable nopvsin as global because it will be used in future patches
as above.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
---
Documentation/admin-guide/kernel-parameters.txt | 5 +++++
arch/x86/include/asm/qspinlock.h | 1 +
arch/x86/kernel/kvm.c | 21 ++++++++++++++-------
kernel/locking/qspinlock.c | 7 +++++++
4 files changed, 27 insertions(+), 7 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c7ac2f3..89d77ea 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5330,6 +5330,11 @@
as generic guest with no PV drivers. Currently support
XEN HVM, KVM, HYPER_V and VMWARE guest.
+ nopvspin [X86,KVM]
+ Disables the qspinlock slow path using PV optimizations
+ which allow the hypervisor to 'idle' the guest on lock
+ contention.
+
xirc2ps_cs= [NET,PCMCIA]
Format:
<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h
index 444d6fd..d86ab94 100644
--- a/arch/x86/include/asm/qspinlock.h
+++ b/arch/x86/include/asm/qspinlock.h
@@ -32,6 +32,7 @@ static __always_inline u32 queued_fetch_set_pending_acquire(struct qspinlock *lo
extern void __pv_init_lock_hash(void);
extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock);
+extern bool nopvspin;
#define queued_spin_unlock queued_spin_unlock
/**
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index e820568..481d879 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -831,16 +831,23 @@ __visible bool __kvm_vcpu_is_preempted(long cpu)
*/
void __init kvm_spinlock_init(void)
{
- /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
- if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
- return;
-
- if (kvm_para_has_hint(KVM_HINTS_REALTIME))
+ /*
+ * Don't use the pvqspinlock code if no KVM_FEATURE_PV_UNHALT feature
+ * support, or there is REALTIME hints or only 1 vCPU.
+ */
+ if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT) ||
+ kvm_para_has_hint(KVM_HINTS_REALTIME) ||
+ num_possible_cpus() == 1) {
+ pr_info("PV spinlocks disabled\n");
return;
+ }
- /* Don't use the pvqspinlock code if there is only 1 vCPU. */
- if (num_possible_cpus() == 1)
+ if (nopvspin) {
+ pr_info("PV spinlocks disabled forced by \"nopvspin\" parameter.\n");
+ static_branch_disable(&virt_spin_lock_key);
return;
+ }
+ pr_info("PV spinlocks enabled\n");
__pv_init_lock_hash();
pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 2473f10..75193d6 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -580,4 +580,11 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
#include "qspinlock_paravirt.h"
#include "qspinlock.c"
+bool nopvspin __initdata;
+static __init int parse_nopvspin(char *arg)
+{
+ nopvspin = true;
+ return 0;
+}
+early_param("nopvspin", parse_nopvspin);
#endif
--
1.8.3.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH v4 1/4] x86/kvm: Add "nopvspin" parameter to disable PV spinlocks
2019-10-03 14:02 ` [PATCH v4 1/4] x86/kvm: Add "nopvspin" parameter to disable PV spinlocks Zhenzhong Duan
@ 2019-10-04 14:52 ` Boris Ostrovsky
2019-10-06 7:49 ` Zhenzhong Duan
0 siblings, 1 reply; 12+ messages in thread
From: Boris Ostrovsky @ 2019-10-04 14:52 UTC (permalink / raw)
To: Zhenzhong Duan, linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, jgross, sstabellini, peterz,
Jonathan Corbet, H. Peter Anvin, Will Deacon
On 10/3/19 10:02 AM, Zhenzhong Duan wrote:
> void __init kvm_spinlock_init(void)
> {
> - /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
> - if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
> - return;
> -
> - if (kvm_para_has_hint(KVM_HINTS_REALTIME))
> + /*
> + * Don't use the pvqspinlock code if no KVM_FEATURE_PV_UNHALT feature
> + * support, or there is REALTIME hints or only 1 vCPU.
> + */
> + if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT) ||
> + kvm_para_has_hint(KVM_HINTS_REALTIME) ||
> + num_possible_cpus() == 1) {
> + pr_info("PV spinlocks disabled\n");
> return;
> + }
>
> - /* Don't use the pvqspinlock code if there is only 1 vCPU. */
> - if (num_possible_cpus() == 1)
> + if (nopvspin) {
> + pr_info("PV spinlocks disabled forced by \"nopvspin\" parameter.\n");
> + static_branch_disable(&virt_spin_lock_key);
Would it make sense to bring here the other site where the key is
disabled (in kvm_smp_prepare_cpus())?
(and, in fact, shouldn't all of the checks that result in early return
above disable the key?)
-boris
> return;
> + }
> + pr_info("PV spinlocks enabled\n");
>
> __pv_init_lock_hash();
> pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v4 1/4] x86/kvm: Add "nopvspin" parameter to disable PV spinlocks
2019-10-04 14:52 ` Boris Ostrovsky
@ 2019-10-06 7:49 ` Zhenzhong Duan
2019-10-07 14:46 ` Boris Ostrovsky
0 siblings, 1 reply; 12+ messages in thread
From: Zhenzhong Duan @ 2019-10-06 7:49 UTC (permalink / raw)
To: Boris Ostrovsky, linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, jgross, sstabellini, peterz,
Jonathan Corbet, H. Peter Anvin, Will Deacon
On 2019/10/4 22:52, Boris Ostrovsky wrote:
> On 10/3/19 10:02 AM, Zhenzhong Duan wrote:
>> void __init kvm_spinlock_init(void)
>> {
>> - /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
>> - if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
>> - return;
>> -
>> - if (kvm_para_has_hint(KVM_HINTS_REALTIME))
>> + /*
>> + * Don't use the pvqspinlock code if no KVM_FEATURE_PV_UNHALT feature
>> + * support, or there is REALTIME hints or only 1 vCPU.
>> + */
>> + if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT) ||
>> + kvm_para_has_hint(KVM_HINTS_REALTIME) ||
>> + num_possible_cpus() == 1) {
>> + pr_info("PV spinlocks disabled\n");
>> return;
>> + }
>>
>> - /* Don't use the pvqspinlock code if there is only 1 vCPU. */
>> - if (num_possible_cpus() == 1)
>> + if (nopvspin) {
>> + pr_info("PV spinlocks disabled forced by \"nopvspin\" parameter.\n");
>> + static_branch_disable(&virt_spin_lock_key);
> Would it make sense to bring here the other site where the key is
> disabled (in kvm_smp_prepare_cpus())?
Thanks for point out, I'll do it. Just not clear if I should do that in a separate patch,
there is a history about that code:
Its original place was here and then moved to kvm_smp_prepare_cpus() by below commit:
34226b6b ("KVM: X86: Fix setup the virt_spin_lock_key before static key get initialized")
which fixed jump_label_init() calling late issue.
Then 8990cac6 ("x86/jump_label: Initialize static branching early") move jump_label_init()
early, so commit 34226b6b could be reverted.
>
> (and, in fact, shouldn't all of the checks that result in early return
> above disable the key?)
I think we should enable he key for !kvm_para_has_feature(KVM_FEATURE_PV_UNHALT) case,
there is lock holder preemption issue as qspinlock is fair lock, virt_spin_lock()
is an optimization to that, imaging one pcpu running 10 vcpus of same guest
contending a same lock.
For kvm_para_has_hint(KVM_HINTS_REALTIME) case, hypervisor hints there is
no preemption and we should disable virt_spin_lock_key to use native qspinlock.
For the UP case, we don't care virt_spin_lock_key value.
For nopvspin case, we intentionally check native qspinlock code performance,
compare it with PV qspinlock, etc. So virt_spin_lock() optimization should be disabled.
Let me know if anything wrong with above understanding. Thanks
Zhenzhong
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v4 1/4] x86/kvm: Add "nopvspin" parameter to disable PV spinlocks
2019-10-06 7:49 ` Zhenzhong Duan
@ 2019-10-07 14:46 ` Boris Ostrovsky
2019-10-08 2:17 ` Zhenzhong Duan
0 siblings, 1 reply; 12+ messages in thread
From: Boris Ostrovsky @ 2019-10-07 14:46 UTC (permalink / raw)
To: Zhenzhong Duan, linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, jgross, sstabellini, peterz,
Jonathan Corbet, H. Peter Anvin, Will Deacon
On 10/6/19 3:49 AM, Zhenzhong Duan wrote:
> On 2019/10/4 22:52, Boris Ostrovsky wrote:
>
>> On 10/3/19 10:02 AM, Zhenzhong Duan wrote:
>>> void __init kvm_spinlock_init(void)
>>> {
>>> - /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
>>> - if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
>>> - return;
>>> -
>>> - if (kvm_para_has_hint(KVM_HINTS_REALTIME))
>>> + /*
>>> + * Don't use the pvqspinlock code if no KVM_FEATURE_PV_UNHALT
>>> feature
>>> + * support, or there is REALTIME hints or only 1 vCPU.
>>> + */
>>> + if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT) ||
>>> + kvm_para_has_hint(KVM_HINTS_REALTIME) ||
>>> + num_possible_cpus() == 1) {
>>> + pr_info("PV spinlocks disabled\n");
>>> return;
>>> + }
>>> - /* Don't use the pvqspinlock code if there is only 1 vCPU. */
>>> - if (num_possible_cpus() == 1)
>>> + if (nopvspin) {
>>> + pr_info("PV spinlocks disabled forced by \"nopvspin\"
>>> parameter.\n");
>>> + static_branch_disable(&virt_spin_lock_key);
>> Would it make sense to bring here the other site where the key is
>> disabled (in kvm_smp_prepare_cpus())?
>
> Thanks for point out, I'll do it. Just not clear if I should do that
> in a separate patch,
> there is a history about that code:
>
> Its original place was here and then moved to kvm_smp_prepare_cpus()
> by below commit:
> 34226b6b ("KVM: X86: Fix setup the virt_spin_lock_key before static
> key get initialized")
> which fixed jump_label_init() calling late issue.
>
> Then 8990cac6 ("x86/jump_label: Initialize static branching early")
> move jump_label_init()
> early, so commit 34226b6b could be reverted.
Which is similar to what you did earlier for Xen.
>
>>
>> (and, in fact, shouldn't all of the checks that result in early return
>> above disable the key?)
>
> I think we should enable he key for
> !kvm_para_has_feature(KVM_FEATURE_PV_UNHALT) case,
> there is lock holder preemption issue as qspinlock is fair lock,
> virt_spin_lock()
> is an optimization to that, imaging one pcpu running 10 vcpus of same
> guest
> contending a same lock.
Right. I conflated pv lock and virt_spin_lock_key, and that is wrong.
-boris
>
> For kvm_para_has_hint(KVM_HINTS_REALTIME) case, hypervisor hints there is
> no preemption and we should disable virt_spin_lock_key to use native
> qspinlock.
>
> For the UP case, we don't care virt_spin_lock_key value.
>
> For nopvspin case, we intentionally check native qspinlock code
> performance,
> compare it with PV qspinlock, etc. So virt_spin_lock() optimization
> should be disabled.
>
> Let me know if anything wrong with above understanding. Thanks
>
> Zhenzhong
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v4 1/4] x86/kvm: Add "nopvspin" parameter to disable PV spinlocks
2019-10-07 14:46 ` Boris Ostrovsky
@ 2019-10-08 2:17 ` Zhenzhong Duan
0 siblings, 0 replies; 12+ messages in thread
From: Zhenzhong Duan @ 2019-10-08 2:17 UTC (permalink / raw)
To: Boris Ostrovsky, linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, jgross, sstabellini, peterz,
Jonathan Corbet, H. Peter Anvin, Will Deacon
On 2019/10/7 22:46, Boris Ostrovsky wrote:
> On 10/6/19 3:49 AM, Zhenzhong Duan wrote:
>> On 2019/10/4 22:52, Boris Ostrovsky wrote:
>>
>>> On 10/3/19 10:02 AM, Zhenzhong Duan wrote:
>>>> void __init kvm_spinlock_init(void)
>>>> {
>>>> - /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
>>>> - if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
>>>> - return;
>>>> -
>>>> - if (kvm_para_has_hint(KVM_HINTS_REALTIME))
>>>> + /*
>>>> + * Don't use the pvqspinlock code if no KVM_FEATURE_PV_UNHALT
>>>> feature
>>>> + * support, or there is REALTIME hints or only 1 vCPU.
>>>> + */
>>>> + if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT) ||
>>>> + kvm_para_has_hint(KVM_HINTS_REALTIME) ||
>>>> + num_possible_cpus() == 1) {
>>>> + pr_info("PV spinlocks disabled\n");
>>>> return;
>>>> + }
>>>> - /* Don't use the pvqspinlock code if there is only 1 vCPU. */
>>>> - if (num_possible_cpus() == 1)
>>>> + if (nopvspin) {
>>>> + pr_info("PV spinlocks disabled forced by \"nopvspin\"
>>>> parameter.\n");
>>>> + static_branch_disable(&virt_spin_lock_key);
>>> Would it make sense to bring here the other site where the key is
>>> disabled (in kvm_smp_prepare_cpus())?
>> Thanks for point out, I'll do it. Just not clear if I should do that
>> in a separate patch,
>> there is a history about that code:
>>
>> Its original place was here and then moved to kvm_smp_prepare_cpus()
>> by below commit:
>> 34226b6b ("KVM: X86: Fix setup the virt_spin_lock_key before static
>> key get initialized")
>> which fixed jump_label_init() calling late issue.
>>
>> Then 8990cac6 ("x86/jump_label: Initialize static branching early")
>> move jump_label_init()
>> early, so commit 34226b6b could be reverted.
> Which is similar to what you did earlier for Xen.
You remember that, ok, I'll do the same for KVM.
Thanks
Zhenzhong
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH v4 2/4] x86/kvm: Change print code to use pr_*() format
2019-10-03 14:02 [PATCH v4 0/4] Add a unified parameter "nopvspin" Zhenzhong Duan
2019-10-03 14:02 ` [PATCH v4 1/4] x86/kvm: Add "nopvspin" parameter to disable PV spinlocks Zhenzhong Duan
@ 2019-10-03 14:02 ` Zhenzhong Duan
2019-10-03 14:02 ` [PATCH v4 3/4] xen: Mark "xen_nopvspin" parameter obsolete Zhenzhong Duan
2019-10-03 14:02 ` [PATCH v4 4/4] x86/hyperv: Mark "hv_nopvspin" " Zhenzhong Duan
3 siblings, 0 replies; 12+ messages in thread
From: Zhenzhong Duan @ 2019-10-03 14:02 UTC (permalink / raw)
To: linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, boris.ostrovsky, jgross, sstabellini,
peterz, Zhenzhong Duan, H. Peter Anvin
pr_*() is preferred than printk(KERN_* ...), after change all the print
in arch/x86/kernel/kvm.c will have "kvm_guest: xxx" style.
No functional change.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
arch/x86/kernel/kvm.c | 30 ++++++++++++++++--------------
1 file changed, 16 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 481d879..a4bfe67 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -7,6 +7,8 @@
* Authors: Anthony Liguori <aliguori@us.ibm.com>
*/
+#define pr_fmt(fmt) "kvm_guest: " fmt
+
#include <linux/context_tracking.h>
#include <linux/init.h>
#include <linux/kernel.h>
@@ -286,8 +288,8 @@ static void kvm_register_steal_time(void)
return;
wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
- pr_info("kvm-stealtime: cpu %d, msr %llx\n",
- cpu, (unsigned long long) slow_virt_to_phys(st));
+ pr_info("stealtime: cpu %d, msr %llx\n", cpu,
+ (unsigned long long) slow_virt_to_phys(st));
}
static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
@@ -321,8 +323,7 @@ static void kvm_guest_cpu_init(void)
wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
__this_cpu_write(apf_reason.enabled, 1);
- printk(KERN_INFO"KVM setup async PF for cpu %d\n",
- smp_processor_id());
+ pr_info("setup async PF for cpu %d\n", smp_processor_id());
}
if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
@@ -347,8 +348,7 @@ static void kvm_pv_disable_apf(void)
wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
__this_cpu_write(apf_reason.enabled, 0);
- printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
- smp_processor_id());
+ pr_info("Unregister pv shared memory for cpu %d\n", smp_processor_id());
}
static void kvm_pv_guest_cpu_reboot(void *unused)
@@ -469,7 +469,8 @@ static void __send_ipi_mask(const struct cpumask *mask, int vector)
} else {
ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
(unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
- WARN_ONCE(ret < 0, "KVM: failed to send PV IPI: %ld", ret);
+ WARN_ONCE(ret < 0, "kvm_guest: failed to send PV IPI: %ld",
+ ret);
min = max = apic_id;
ipi_bitmap = 0;
}
@@ -479,7 +480,8 @@ static void __send_ipi_mask(const struct cpumask *mask, int vector)
if (ipi_bitmap) {
ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
(unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
- WARN_ONCE(ret < 0, "KVM: failed to send PV IPI: %ld", ret);
+ WARN_ONCE(ret < 0, "kvm_guest: failed to send PV IPI: %ld",
+ ret);
}
local_irq_restore(flags);
@@ -509,7 +511,7 @@ static void kvm_setup_pv_ipi(void)
{
apic->send_IPI_mask = kvm_send_ipi_mask;
apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
- pr_info("KVM setup pv IPIs\n");
+ pr_info("setup pv IPIs\n");
}
static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
@@ -639,11 +641,11 @@ static void __init kvm_guest_init(void)
!kvm_para_has_hint(KVM_HINTS_REALTIME) &&
kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
- pr_info("KVM setup pv sched yield\n");
+ pr_info("setup pv sched yield\n");
}
if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
kvm_cpu_online, kvm_cpu_down_prepare) < 0)
- pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");
+ pr_err("failed to install cpu hotplug callbacks\n");
#else
sev_map_percpu_data();
kvm_guest_cpu_init();
@@ -746,7 +748,7 @@ static __init int kvm_setup_pv_tlb_flush(void)
zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu),
GFP_KERNEL, cpu_to_node(cpu));
}
- pr_info("KVM setup pv remote TLB flush\n");
+ pr_info("setup pv remote TLB flush\n");
}
return 0;
@@ -879,8 +881,8 @@ static void kvm_enable_host_haltpoll(void *i)
void arch_haltpoll_enable(unsigned int cpu)
{
if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
- pr_err_once("kvm: host does not support poll control\n");
- pr_err_once("kvm: host upgrade recommended\n");
+ pr_err_once("host does not support poll control\n");
+ pr_err_once("host upgrade recommended\n");
return;
}
--
1.8.3.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH v4 3/4] xen: Mark "xen_nopvspin" parameter obsolete
2019-10-03 14:02 [PATCH v4 0/4] Add a unified parameter "nopvspin" Zhenzhong Duan
2019-10-03 14:02 ` [PATCH v4 1/4] x86/kvm: Add "nopvspin" parameter to disable PV spinlocks Zhenzhong Duan
2019-10-03 14:02 ` [PATCH v4 2/4] x86/kvm: Change print code to use pr_*() format Zhenzhong Duan
@ 2019-10-03 14:02 ` Zhenzhong Duan
2019-10-04 14:57 ` Boris Ostrovsky
2019-10-03 14:02 ` [PATCH v4 4/4] x86/hyperv: Mark "hv_nopvspin" " Zhenzhong Duan
3 siblings, 1 reply; 12+ messages in thread
From: Zhenzhong Duan @ 2019-10-03 14:02 UTC (permalink / raw)
To: linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, boris.ostrovsky, jgross, sstabellini,
peterz, Zhenzhong Duan, Jonathan Corbet, H. Peter Anvin
Map "xen_nopvspin" to "nopvspin", fix stale description of "xen_nopvspin"
as we use qspinlock now.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
Documentation/admin-guide/kernel-parameters.txt | 7 ++++---
arch/x86/xen/spinlock.c | 3 +++
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 89d77ea..df1eacc 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5303,8 +5303,9 @@
never -- do not unplug even if version check succeeds
xen_nopvspin [X86,XEN]
- Disables the ticketlock slowpath using Xen PV
- optimizations.
+ Disables the qspinlock slowpath using Xen PV optimizations.
+ This parameter is obsoleted by "nopvspin" parameter, which
+ has equivalent effect for XEN platform.
xen_nopv [X86]
Disables the PV optimizations forcing the HVM guest to
@@ -5330,7 +5331,7 @@
as generic guest with no PV drivers. Currently support
XEN HVM, KVM, HYPER_V and VMWARE guest.
- nopvspin [X86,KVM]
+ nopvspin [X86,XEN,KVM]
Disables the qspinlock slow path using PV optimizations
which allow the hypervisor to 'idle' the guest on lock
contention.
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 6deb490..bae29a4 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -114,6 +114,8 @@ void xen_uninit_lock_cpu(int cpu)
*/
void __init xen_init_spinlocks(void)
{
+ if (nopvspin)
+ xen_pvspin = false;
/* Don't need to use pvqspinlock code if there is only 1 vCPU. */
if (num_possible_cpus() == 1)
@@ -137,6 +139,7 @@ void __init xen_init_spinlocks(void)
static __init int xen_parse_nopvspin(char *arg)
{
+ pr_notice("\"xen_nopvspin\" is deprecated, please use \"nopvspin\" instead\n");
xen_pvspin = false;
return 0;
}
--
1.8.3.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH v4 3/4] xen: Mark "xen_nopvspin" parameter obsolete
2019-10-03 14:02 ` [PATCH v4 3/4] xen: Mark "xen_nopvspin" parameter obsolete Zhenzhong Duan
@ 2019-10-04 14:57 ` Boris Ostrovsky
2019-10-06 7:52 ` Zhenzhong Duan
0 siblings, 1 reply; 12+ messages in thread
From: Boris Ostrovsky @ 2019-10-04 14:57 UTC (permalink / raw)
To: Zhenzhong Duan, linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, jgross, sstabellini, peterz,
Jonathan Corbet, H. Peter Anvin
On 10/3/19 10:02 AM, Zhenzhong Duan wrote:
> Map "xen_nopvspin" to "nopvspin", fix stale description of "xen_nopvspin"
> as we use qspinlock now.
>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Juergen Gross <jgross@suse.com>
> Cc: Stefano Stabellini <sstabellini@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
with a small nit
> void __init xen_init_spinlocks(void)
> {
> + if (nopvspin)
> + xen_pvspin = false;
>
> /* Don't need to use pvqspinlock code if there is only 1 vCPU. */
> if (num_possible_cpus() == 1)
I'd fold the change into this 'if' statement, I think it will still be
clear what the comment refers to.
-boris
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v4 3/4] xen: Mark "xen_nopvspin" parameter obsolete
2019-10-04 14:57 ` Boris Ostrovsky
@ 2019-10-06 7:52 ` Zhenzhong Duan
0 siblings, 0 replies; 12+ messages in thread
From: Zhenzhong Duan @ 2019-10-06 7:52 UTC (permalink / raw)
To: Boris Ostrovsky, linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, jgross, sstabellini, peterz,
Jonathan Corbet, H. Peter Anvin
On 2019/10/4 22:57, Boris Ostrovsky wrote:
> On 10/3/19 10:02 AM, Zhenzhong Duan wrote:
>> Map "xen_nopvspin" to "nopvspin", fix stale description of "xen_nopvspin"
>> as we use qspinlock now.
>>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
>> Cc: Jonathan Corbet <corbet@lwn.net>
>> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>> Cc: Juergen Gross <jgross@suse.com>
>> Cc: Stefano Stabellini <sstabellini@kernel.org>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Borislav Petkov <bp@alien8.de>
>> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>
> with a small nit
>
>> void __init xen_init_spinlocks(void)
>> {
>> + if (nopvspin)
>> + xen_pvspin = false;
>>
>> /* Don't need to use pvqspinlock code if there is only 1 vCPU. */
>> if (num_possible_cpus() == 1)
> I'd fold the change into this 'if' statement, I think it will still be
> clear what the comment refers to.
Good suggestion, will do that. Thanks
Zhenzhong
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH v4 4/4] x86/hyperv: Mark "hv_nopvspin" parameter obsolete
2019-10-03 14:02 [PATCH v4 0/4] Add a unified parameter "nopvspin" Zhenzhong Duan
` (2 preceding siblings ...)
2019-10-03 14:02 ` [PATCH v4 3/4] xen: Mark "xen_nopvspin" parameter obsolete Zhenzhong Duan
@ 2019-10-03 14:02 ` Zhenzhong Duan
2019-10-05 17:07 ` Michael Kelley
3 siblings, 1 reply; 12+ messages in thread
From: Zhenzhong Duan @ 2019-10-03 14:02 UTC (permalink / raw)
To: linux-kernel
Cc: vkuznets, linux-hyperv, kvm, kys, haiyangz, sthemmin, sashal,
tglx, mingo, bp, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, boris.ostrovsky, jgross, sstabellini,
peterz, Zhenzhong Duan, Jonathan Corbet, H. Peter Anvin
Map "hv_nopvspin" to "nopvspin".
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
Documentation/admin-guide/kernel-parameters.txt | 6 +++++-
arch/x86/hyperv/hv_spinlock.c | 4 ++++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index df1eacc..08c6d34 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1436,6 +1436,10 @@
hv_nopvspin [X86,HYPER_V] Disables the paravirt spinlock optimizations
which allow the hypervisor to 'idle' the
guest on lock contention.
+ This parameter is obsoleted by "nopvspin"
+ parameter, which has equivalent effect for
+ HYPER_V platform.
+
keep_bootcon [KNL]
Do not unregister boot console at start. This is only
@@ -5331,7 +5335,7 @@
as generic guest with no PV drivers. Currently support
XEN HVM, KVM, HYPER_V and VMWARE guest.
- nopvspin [X86,XEN,KVM]
+ nopvspin [X86,XEN,KVM,HYPER_V]
Disables the qspinlock slow path using PV optimizations
which allow the hypervisor to 'idle' the guest on lock
contention.
diff --git a/arch/x86/hyperv/hv_spinlock.c b/arch/x86/hyperv/hv_spinlock.c
index 07f21a0..47c7d6c 100644
--- a/arch/x86/hyperv/hv_spinlock.c
+++ b/arch/x86/hyperv/hv_spinlock.c
@@ -64,6 +64,9 @@ __visible bool hv_vcpu_is_preempted(int vcpu)
void __init hv_init_spinlocks(void)
{
+ if (nopvspin)
+ hv_pvspin = false;
+
if (!hv_pvspin || !apic ||
!(ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) ||
!(ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE)) {
@@ -82,6 +85,7 @@ void __init hv_init_spinlocks(void)
static __init int hv_parse_nopvspin(char *arg)
{
+ pr_notice("\"hv_nopvspin\" is deprecated, please use \"nopvspin\" instead\n");
hv_pvspin = false;
return 0;
}
--
1.8.3.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* RE: [PATCH v4 4/4] x86/hyperv: Mark "hv_nopvspin" parameter obsolete
2019-10-03 14:02 ` [PATCH v4 4/4] x86/hyperv: Mark "hv_nopvspin" " Zhenzhong Duan
@ 2019-10-05 17:07 ` Michael Kelley
0 siblings, 0 replies; 12+ messages in thread
From: Michael Kelley @ 2019-10-05 17:07 UTC (permalink / raw)
To: Zhenzhong Duan, linux-kernel
Cc: vkuznets, linux-hyperv, kvm, KY Srinivasan, Haiyang Zhang,
Stephen Hemminger, sashal, tglx, mingo, bp, pbonzini, rkrcmar,
sean.j.christopherson, wanpengli, jmattson, joro,
boris.ostrovsky, jgross, sstabellini, peterz, Jonathan Corbet,
H. Peter Anvin
From: Zhenzhong Duan <zhenzhong.duan@oracle.com> Sent: Thursday, October 3, 2019 7:02 AM
>
> Map "hv_nopvspin" to "nopvspin".
>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: Stephen Hemminger <sthemmin@microsoft.com>
> Cc: Sasha Levin <sashal@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 6 +++++-
> arch/x86/hyperv/hv_spinlock.c | 4 ++++
> 2 files changed, 9 insertions(+), 1 deletion(-)
>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
^ permalink raw reply [flat|nested] 12+ messages in thread