Re: [patch-rt] kvm: Convert pvclock_gtod_sync_lock to raw_spinlock_t

2017-01-20 Thread Mike Galbraith 
On Fri, 2017-01-20 at 17:44 +0100, Sebastian Andrzej Siewior wrote:

> kvm_make_mclock_inprogress_request() will do zalloc_cpumask_var().
> off-stack zalloc is not yet working but I would like to enable it. Also
> it does a SMP function call.
> 
> Couldn't we go the other way around and drop the local_irq_disable()?

I suppose so.

-MIke

Re: [patch-rt] kvm: Convert pvclock_gtod_sync_lock to raw_spinlock_t

2017-01-20 Thread Sebastian Andrzej Siewior 
On 2016-12-26 07:54:08 [+0100], Mike Galbraith wrote:

Not so sure about it.

> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1540,7 +1540,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu
>   kvm_vcpu_write_tsc_offset(vcpu, offset);
>   raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
>  
> - spin_lock(&kvm->arch.pvclock_gtod_sync_lock);
> + raw_spin_lock(&kvm->arch.pvclock_gtod_sync_lock);
>   if (!matched) {
>   kvm->arch.nr_vcpus_matched_tsc = 0;
>   } else if (!already_matched) {
> @@ -1548,7 +1548,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu
>   }
>  
>   kvm_track_tsc_matching(vcpu);
> - spin_unlock(&kvm->arch.pvclock_gtod_sync_lock);
> + raw_spin_unlock(&kvm->arch.pvclock_gtod_sync_lock);
>  }
>  
>  EXPORT_SYMBOL_GPL(kvm_write_tsc);
> @@ -1715,7 +1715,7 @@ static void kvm_gen_update_masterclock(s
>   struct kvm_vcpu *vcpu;
>   struct kvm_arch *ka = &kvm->arch;
>  
> - spin_lock(&ka->pvclock_gtod_sync_lock);
> + raw_spin_lock(&ka->pvclock_gtod_sync_lock);
>   kvm_make_mclock_inprogress_request(kvm);

kvm_make_mclock_inprogress_request() will do zalloc_cpumask_var().
off-stack zalloc is not yet working but I would like to enable it. Also
it does a SMP function call.

Couldn't we go the other way around and drop the local_irq_disable()?

Sebastian

[patch-rt] kvm: Convert pvclock_gtod_sync_lock to raw_spinlock_t

2016-12-25 Thread Mike Galbraith 
Fix splat below.  Lock is short hold, make it raw.

[15528.614216] BUG: sleeping function called from invalid context at 
kernel/locking/rtmutex.c:995
[15528.614218] in_atomic(): 0, irqs_disabled(): 1, pid: 19619, name: 
qemu-system-x86
[15528.614218] no locks held by qemu-system-x86/19619.
[15528.614219] irq event stamp: 321840
[15528.614224] hardirqs last  enabled at (321839): [] 
entry_SYSCALL_64_fastpath+0x5/0xc2
[15528.614244] hardirqs last disabled at (321840): [] 
kvm_arch_vm_ioctl+0x234/0xda0 [kvm]
[15528.614246] softirqs last  enabled at (0): [] 
copy_process.part.36+0x5ba/0x20b0
[15528.614247] softirqs last disabled at (0): [<  (null)>]   
(null)
[15528.614250] CPU: 7 PID: 19619 Comm: qemu-system-x86 Tainted: GE  
 4.9.0-rt1-virgin #1
[15528.614250] Hardware name: MEDION MS-7848/MS-7848, BIOS M7848W08.20C 
09/23/2013
[15528.614253]  c9000b98bc30 8136874d  
8803e76db200
[15528.614255]  c9000b98bc68 810abe9d 8800353472d0 
8800353472d0
[15528.614257]  7ffc53dbc2b0 000b 7ffc53dbc2b0 
c9000b98bc88
[15528.614257] Call Trace:
[15528.614262]  [] dump_stack+0x85/0xc8
[15528.614266]  [] ___might_sleep+0x15d/0x260
[15528.614268]  [] rt_spin_lock+0x24/0x80
[15528.614283]  [] __get_kvmclock_ns+0x22/0xf0 [kvm]
[15528.614297]  [] kvm_arch_vm_ioctl+0x23c/0xda0 [kvm]
[15528.614300]  [] ? __lock_acquire+0x305/0x16a0
[15528.614301]  [] ? unpin_current_cpu+0x16/0x70
[15528.614314]  [] kvm_vm_ioctl+0x9d/0x920 [kvm]
[15528.614316]  [] ? __fget+0x107/0x220
[15528.614318]  [] ? __lock_is_held+0x49/0x70
[15528.614320]  [] do_vfs_ioctl+0x96/0x6c0
[15528.614321]  [] ? __fget+0x124/0x220
[15528.614322]  [] ? __fget+0x5/0x220
[15528.614324]  [] SyS_ioctl+0x41/0x70
[15528.614326]  [] entry_SYSCALL_64_fastpath+0x1f/0xc2

Signed-off-by: Mike Galbraith 
---
 arch/x86/include/asm/kvm_host.h |2 +-
 arch/x86/kvm/x86.c  |   20 ++--
 2 files changed, 11 insertions(+), 11 deletions(-)

--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -755,7 +755,7 @@ struct kvm_arch {
u64 cur_tsc_generation;
int nr_vcpus_matched_tsc;
 
-   spinlock_t pvclock_gtod_sync_lock;
+   raw_spinlock_t pvclock_gtod_sync_lock;
bool use_master_clock;
u64 master_kernel_ns;
cycle_t master_cycle_now;
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1540,7 +1540,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu
kvm_vcpu_write_tsc_offset(vcpu, offset);
raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
 
-   spin_lock(&kvm->arch.pvclock_gtod_sync_lock);
+   raw_spin_lock(&kvm->arch.pvclock_gtod_sync_lock);
if (!matched) {
kvm->arch.nr_vcpus_matched_tsc = 0;
} else if (!already_matched) {
@@ -1548,7 +1548,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu
}
 
kvm_track_tsc_matching(vcpu);
-   spin_unlock(&kvm->arch.pvclock_gtod_sync_lock);
+   raw_spin_unlock(&kvm->arch.pvclock_gtod_sync_lock);
 }
 
 EXPORT_SYMBOL_GPL(kvm_write_tsc);
@@ -1715,7 +1715,7 @@ static void kvm_gen_update_masterclock(s
struct kvm_vcpu *vcpu;
struct kvm_arch *ka = &kvm->arch;
 
-   spin_lock(&ka->pvclock_gtod_sync_lock);
+   raw_spin_lock(&ka->pvclock_gtod_sync_lock);
kvm_make_mclock_inprogress_request(kvm);
/* no guest entries from this point */
pvclock_update_vm_gtod_copy(kvm);
@@ -1727,7 +1727,7 @@ static void kvm_gen_update_masterclock(s
kvm_for_each_vcpu(i, vcpu, kvm)
clear_bit(KVM_REQ_MCLOCK_INPROGRESS, &vcpu->requests);
 
-   spin_unlock(&ka->pvclock_gtod_sync_lock);
+   raw_spin_unlock(&ka->pvclock_gtod_sync_lock);
 #endif
 }
 
@@ -1736,15 +1736,15 @@ static u64 __get_kvmclock_ns(struct kvm
struct kvm_arch *ka = &kvm->arch;
struct pvclock_vcpu_time_info hv_clock;
 
-   spin_lock(&ka->pvclock_gtod_sync_lock);
+   raw_spin_lock(&ka->pvclock_gtod_sync_lock);
if (!ka->use_master_clock) {
-   spin_unlock(&ka->pvclock_gtod_sync_lock);
+   raw_spin_unlock(&ka->pvclock_gtod_sync_lock);
return ktime_get_boot_ns() + ka->kvmclock_offset;
}
 
hv_clock.tsc_timestamp = ka->master_cycle_now;
hv_clock.system_time = ka->master_kernel_ns + ka->kvmclock_offset;
-   spin_unlock(&ka->pvclock_gtod_sync_lock);
+   raw_spin_unlock(&ka->pvclock_gtod_sync_lock);
 
kvm_get_time_scale(NSEC_PER_SEC, __this_cpu_read(cpu_tsc_khz) * 1000LL,
   &hv_clock.tsc_shift,
@@ -1835,13 +1835,13 @@ static int kvm_guest_time_update(struct
 * If the host uses TSC clock, then passthrough TSC as stable
 * to the guest.
 */
-   spin_lock(&ka->pvclock_gtod_sync_lock);
+   raw_spin_lock(&ka->pvclock_gtod_sync_lock);
use_master_clock = ka->use_master_clock;
if (use_master_clock) {