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[PATCH 0/4 V16] Avoid soft lockup message when KVM is stopped by host
Changes from V15: Add arch/*/include/asm/kvm_para.h that includes the asm-generic version Changes from V14: Update documentation for the pvclock api Changes from V13: Expand on KVM_KVMCLOCK_CTRL ioctl documentation Changes from V12: Re-add missing kvm.c code after rebase Rename CAP to KVM_CAP_KVMCLOCK_CTRL Rename ioctl to KVM_KVMCLOCK_CTRL Changes from V11: Re-add asm-generic stub Correct api.txt typo add kvm_make_request() call after setting PVCLOCK_GUEST_STOPPED Changes from V10: Return ioctl to per vcpu instead of per vm Changes from V9: Use kvm_for_each_vcpu to iterate online vcpu's Changes from V8: Make KVM_GUEST_PAUSED a per vm ioctl instead of per vcpu Changes from V7: Define KVM_CAP_GUEST_PAUSED and support check Call mark_page_dirty () after setting PVCLOCK_GUEST_STOPPED Changes from V6: Use __this_cpu_and when clearing the PVCLOCK_GUEST_STOPPED flag Changes from V5: Collapse generic check_and_clear_guest_stopped into patch 2 Include check_and_clear_guest_stopped defintion to ia64, s390, and powerpc Change check_and_clear_guest_stopped to use __get_cpu_var instead of taking the cpuid arg. Protect check_and_clear_guest_stopped declaration with CONFIG_KVM_CLOCK check Changes from V4: Rename KVM_GUEST_PAUSED to KVMCLOCK_GUEST_PAUSED Add description of KVMCLOCK_GUEST_PAUSED ioctl to api.txt Changes from V3: Include CC's on patch 3 Drop clear flag ioctl and have the watchdog clear the flag when it is reset Changes from V2: A new kvm functions defined in kvm_para.h, the only change to pvclock is the initial flag definition Changes from V1: (Thanks Marcelo) Host code has all been moved to arch/x86/kvm/x86.c KVM_PAUSE_GUEST was renamed to KVM_GUEST_PAUSED When a guest kernel is stopped by the host hypervisor it can look like a soft lockup to the guest kernel. This false warning can mask later soft lockup warnings which may be real. This patch series adds a method for a host hypervisor to communicate to a guest kernel that it is being stopped. The final patch in the series has the watchdog check this flag when it goes to issue a soft lockup warning and skip the warning if the guest knows it was stopped. It was attempted to solve this in Qemu, but the side effects of saving and restoring the clock and tsc for each vcpu put the wall clock of the guest behind by the amount of time of the pause. This forces a guest to have ntp running in order to keep the wall clock accurate. Cc: mi...@redhat.com Cc: h...@zytor.com Cc: ry...@linux.vnet.ibm.com Cc: aligu...@us.ibm.com Cc: mtosa...@redhat.com Cc: kvm@vger.kernel.org Cc: linux-a...@vger.kernel.org Cc: x...@kernel.org Cc: linux-ker...@vger.kernel.org Eric B Munson (4): Add flag to indicate that a vm was stopped by the host Add functions to check if the host has stopped the vm Add ioctl for KVM_KVMCLOCK_CTRL Add check for suspended vm in softlockup detector Documentation/virtual/kvm/api.txt | 20 Documentation/virtual/kvm/msr.txt |4 arch/alpha/include/asm/kvm_para.h |1 + arch/arm/include/asm/kvm_para.h|1 + arch/avr32/include/asm/kvm_para.h |1 + arch/blackfin/include/asm/kvm_para.h |1 + arch/c6x/include/asm/kvm_para.h|1 + arch/frv/include/asm/kvm_para.h|1 + arch/h8300/include/asm/kvm_para.h |1 + arch/hexagon/include/asm/kvm_para.h|1 + arch/ia64/include/asm/kvm_para.h |5 + arch/m68k/include/asm/kvm_para.h |1 + arch/microblaze/include/asm/kvm_para.h |1 + arch/mips/include/asm/kvm_para.h |1 + arch/mn10300/include/asm/kvm_para.h|1 + arch/openrisc/include/asm/kvm_para.h |1 + arch/parisc/include/asm/kvm_para.h |1 + arch/powerpc/include/asm/kvm_para.h|5 + arch/s390/include/asm/kvm_para.h |5 + arch/score/include/asm/kvm_para.h |1 + arch/sh/include/asm/kvm_para.h |1 + arch/sparc/include/asm/kvm_para.h |1 + arch/tile/include/asm/kvm_para.h |1 + arch/um/include/asm/kvm_para.h |1 + arch/unicore32/include/asm/kvm_para.h |1 + arch/x86/include/asm/kvm_para.h|8 arch/x86/include/asm/pvclock-abi.h |1 + arch/x86/kernel/kvmclock.c | 21 + arch/x86/kvm/x86.c | 22 ++ arch/xtensa/include/asm/kvm_para.h |1 + include/asm-generic/kvm_para.h | 14 ++ include/linux/kvm.h|3 +++ kernel/watchdog.c | 12 33 files changed, 141 insertions(+), 0 deletions(-) create mode 100644 arch/alpha/include/asm/kvm_para.h create mode 100644 arch/arm/include/asm/kvm_para.h create mode 100644 arch/avr32/include/asm/kvm_para.h create mode 100644 arch/blackfin/include/asm/kvm_para.h create mode 100644 arch/c6x/include/asm/kvm_para.h create mode 100644 arch/frv/include/asm/kvm_para.h create mode
[PATCH 1/4 V16] Add flag to indicate that a vm was stopped by the host
This flag will be used to check if the vm was stopped by the host when a soft
lockup was detected. The host will set the flag when it stops the guest. On
resume, the guest will check this flag if a soft lockup is detected and skip
issuing the warning.
Signed-off-by: Eric B Munson emun...@mgebm.net
Cc: mi...@redhat.com
Cc: h...@zytor.com
Cc: ry...@linux.vnet.ibm.com
Cc: aligu...@us.ibm.com
Cc: mtosa...@redhat.com
Cc: kvm@vger.kernel.org
Cc: linux-a...@vger.kernel.org
Cc: x...@kernel.org
Cc: linux-ker...@vger.kernel.org
---
arch/x86/include/asm/pvclock-abi.h |1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/pvclock-abi.h
b/arch/x86/include/asm/pvclock-abi.h
index 35f2d19..6167fd7 100644
--- a/arch/x86/include/asm/pvclock-abi.h
+++ b/arch/x86/include/asm/pvclock-abi.h
@@ -40,5 +40,6 @@ struct pvclock_wall_clock {
} __attribute__((__packed__));
#define PVCLOCK_TSC_STABLE_BIT (1 0)
+#define PVCLOCK_GUEST_STOPPED (1 1)
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_PVCLOCK_ABI_H */
--
1.7.5.4
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[PATCH 3/4 V16] Add ioctl for KVM_KVMCLOCK_CTRL
Now that we have a flag that will tell the guest it was suspended, create an
interface for that communication using a KVM ioctl.
Signed-off-by: Eric B Munson emun...@mgebm.net
Cc: mi...@redhat.com
Cc: h...@zytor.com
Cc: ry...@linux.vnet.ibm.com
Cc: aligu...@us.ibm.com
Cc: mtosa...@redhat.com
Cc: kvm@vger.kernel.org
Cc: linux-a...@vger.kernel.org
Cc: x...@kernel.org
Cc: linux-ker...@vger.kernel.org
---
Changes from V14:
Add description of flags bit used for host-guest communication
Changes from V13:
Expand the ioctl documentation
Changes from V12:
Rename KVM_CAP and KVM ioctl
Changes from V11:
Correct typo in api.txt
Add kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu) call to kvm_set_guest_paused()
Changes from V10:
Return the ioctl to per vcpu instead of per vm
Changes from V9:
Use kvm_for_each_vcpu to iterate online vcpu's
Changes from V8:
Make KVM_GUEST_PAUSED a per vm ioctl instead of per vcpu
Changes from V7:
Define KVM_CAP_GUEST_PAUSED and support check
Call mark_page_dirty () after setting PVCLOCK_GUEST_STOPPED
Changes from V4:
Rename KVM_GUEST_PAUSED to KVMCLOCK_GUEST_PAUSED
Add new ioctl description to api.txt
Documentation/virtual/kvm/api.txt | 20
Documentation/virtual/kvm/msr.txt |4
arch/x86/kvm/x86.c| 22 ++
include/linux/kvm.h |3 +++
4 files changed, 49 insertions(+), 0 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt
b/Documentation/virtual/kvm/api.txt
index 6386f8c..81ff39f 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1669,6 +1669,26 @@ at the memory location pointed to by addr.
The list of registers accessible using this interface is identical to the
list in 4.64.
+4.70 KVM_KVMCLOCK_CTRL
+
+Capability: KVM_CAP_KVMCLOCK_CTRL
+Architectures: Any that implement pvclocks (currently x86 only)
+Type: vcpu ioctl
+Parameters: None
+Returns: 0 on success, -1 on error
+
+This signals to the host kernel that the specified guest is being paused by
+userspace. The host will set a flag in the pvclock structure that is checked
+from the soft lockup watchdog. The flag is part of the pvclock structure that
+is shared between guest and host, specifically the second bit of the flags
+field of the pvclock_vcpu_time_info structure. It will be set exclusively by
+the host and read/cleared exclusively by the guest. The guest operation of
+checking and clearing the flag must an atomic operation so
+load-link/store-conditional, or equivalent must be used. There are two cases
+where the guest will clear the flag: when the soft lockup watchdog timer resets
+itself or when a soft lockup is detected. This ioctl can be called any time
+after pausing the vcpu, but before it is resumed.
+
5. The kvm_run structure
Application code obtains a pointer to the kvm_run structure by
diff --git a/Documentation/virtual/kvm/msr.txt
b/Documentation/virtual/kvm/msr.txt
index 5031780..96b41bd 100644
--- a/Documentation/virtual/kvm/msr.txt
+++ b/Documentation/virtual/kvm/msr.txt
@@ -109,6 +109,10 @@ MSR_KVM_SYSTEM_TIME_NEW: 0x4b564d01
0 | 24 | multiple cpus are guaranteed to
| | be monotonic
-
+ | | guest vcpu has been paused by
+1 | N/A | the host
+ | | See 4.70 in api.txt
+ -
Availability of this MSR must be checked via bit 3 in 0x401 cpuid
leaf prior to usage.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7ce5878..4e1bf3b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2145,6 +2145,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_ASYNC_PF:
case KVM_CAP_GET_TSC_KHZ:
case KVM_CAP_PCI_2_3:
+ case KVM_CAP_KVMCLOCK_CTRL:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -2595,6 +2596,23 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu
*vcpu,
return r;
}
+/*
+ * kvm_set_guest_paused() indicates to the guest kernel that it has been
+ * stopped by the hypervisor. This function will be called from the host only.
+ * EINVAL is returned when the host attempts to set the flag for a guest that
+ * does not support pv clocks.
+ */
+static int kvm_set_guest_paused(struct kvm_vcpu *vcpu)
+{
+ struct pvclock_vcpu_time_info *src = vcpu-arch.hv_clock;
+ if (!vcpu-arch.time_page)
+ return -EINVAL;
+ src-flags |= PVCLOCK_GUEST_STOPPED;
+ mark_page_dirty(vcpu-kvm, vcpu-arch.time PAGE_SHIFT);
+ kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
+ return 0;
+}
+
long kvm_arch_vcpu_ioctl(struct file *filp,
unsigned int ioctl,
[PATCH 2/4 V16] Add functions to check if the host has stopped the vm
When a host stops or suspends a VM it will set a flag to show this. The watchdog will use these functions to determine if a softlockup is real, or the result of a suspended VM. Signed-off-by: Eric B Munson emun...@mgebm.net asm-generic changes Acked-by: Arnd Bergmann a...@arndb.de Cc: mi...@redhat.com Cc: h...@zytor.com Cc: ry...@linux.vnet.ibm.com Cc: aligu...@us.ibm.com Cc: mtosa...@redhat.com Cc: kvm@vger.kernel.org Cc: linux-a...@vger.kernel.org Cc: x...@kernel.org Cc: linux-ker...@vger.kernel.org --- Changes from V15: Add stubs to include asm-generic/kvm_para.h where necessary Changes from V11: Re-add the missing asm-generic stub for check_and_clear_guest_stopped() Changes from V6: Use __this_cpu_and when clearing the PVCLOCK_GUEST_STOPPED flag Changes from V5: Collapse generic stubs into this patch check_and_clear_guest_stopped() takes no args and uses __get_cpu_var() Include individual definitions in ia64, s390, and powerpc arch/alpha/include/asm/kvm_para.h |1 + arch/arm/include/asm/kvm_para.h|1 + arch/avr32/include/asm/kvm_para.h |1 + arch/blackfin/include/asm/kvm_para.h |1 + arch/c6x/include/asm/kvm_para.h|1 + arch/frv/include/asm/kvm_para.h|1 + arch/h8300/include/asm/kvm_para.h |1 + arch/hexagon/include/asm/kvm_para.h|1 + arch/ia64/include/asm/kvm_para.h |5 + arch/m68k/include/asm/kvm_para.h |1 + arch/microblaze/include/asm/kvm_para.h |1 + arch/mips/include/asm/kvm_para.h |1 + arch/mn10300/include/asm/kvm_para.h|1 + arch/openrisc/include/asm/kvm_para.h |1 + arch/parisc/include/asm/kvm_para.h |1 + arch/powerpc/include/asm/kvm_para.h|5 + arch/s390/include/asm/kvm_para.h |5 + arch/score/include/asm/kvm_para.h |1 + arch/sh/include/asm/kvm_para.h |1 + arch/sparc/include/asm/kvm_para.h |1 + arch/tile/include/asm/kvm_para.h |1 + arch/um/include/asm/kvm_para.h |1 + arch/unicore32/include/asm/kvm_para.h |1 + arch/x86/include/asm/kvm_para.h|8 arch/x86/kernel/kvmclock.c | 21 + arch/xtensa/include/asm/kvm_para.h |1 + include/asm-generic/kvm_para.h | 14 ++ 27 files changed, 79 insertions(+), 0 deletions(-) create mode 100644 arch/alpha/include/asm/kvm_para.h create mode 100644 arch/arm/include/asm/kvm_para.h create mode 100644 arch/avr32/include/asm/kvm_para.h create mode 100644 arch/blackfin/include/asm/kvm_para.h create mode 100644 arch/c6x/include/asm/kvm_para.h create mode 100644 arch/frv/include/asm/kvm_para.h create mode 100644 arch/h8300/include/asm/kvm_para.h create mode 100644 arch/hexagon/include/asm/kvm_para.h create mode 100644 arch/m68k/include/asm/kvm_para.h create mode 100644 arch/microblaze/include/asm/kvm_para.h create mode 100644 arch/mips/include/asm/kvm_para.h create mode 100644 arch/mn10300/include/asm/kvm_para.h create mode 100644 arch/openrisc/include/asm/kvm_para.h create mode 100644 arch/parisc/include/asm/kvm_para.h create mode 100644 arch/score/include/asm/kvm_para.h create mode 100644 arch/sh/include/asm/kvm_para.h create mode 100644 arch/sparc/include/asm/kvm_para.h create mode 100644 arch/tile/include/asm/kvm_para.h create mode 100644 arch/um/include/asm/kvm_para.h create mode 100644 arch/unicore32/include/asm/kvm_para.h create mode 100644 arch/xtensa/include/asm/kvm_para.h create mode 100644 include/asm-generic/kvm_para.h diff --git a/arch/alpha/include/asm/kvm_para.h b/arch/alpha/include/asm/kvm_para.h new file mode 100644 index 000..14fab8f --- /dev/null +++ b/arch/alpha/include/asm/kvm_para.h @@ -0,0 +1 @@ +#include asm-generic/kvm_para.h diff --git a/arch/arm/include/asm/kvm_para.h b/arch/arm/include/asm/kvm_para.h new file mode 100644 index 000..14fab8f --- /dev/null +++ b/arch/arm/include/asm/kvm_para.h @@ -0,0 +1 @@ +#include asm-generic/kvm_para.h diff --git a/arch/avr32/include/asm/kvm_para.h b/arch/avr32/include/asm/kvm_para.h new file mode 100644 index 000..14fab8f --- /dev/null +++ b/arch/avr32/include/asm/kvm_para.h @@ -0,0 +1 @@ +#include asm-generic/kvm_para.h diff --git a/arch/blackfin/include/asm/kvm_para.h b/arch/blackfin/include/asm/kvm_para.h new file mode 100644 index 000..14fab8f --- /dev/null +++ b/arch/blackfin/include/asm/kvm_para.h @@ -0,0 +1 @@ +#include asm-generic/kvm_para.h diff --git a/arch/c6x/include/asm/kvm_para.h b/arch/c6x/include/asm/kvm_para.h new file mode 100644 index 000..14fab8f --- /dev/null +++ b/arch/c6x/include/asm/kvm_para.h @@ -0,0 +1 @@ +#include asm-generic/kvm_para.h diff --git a/arch/frv/include/asm/kvm_para.h b/arch/frv/include/asm/kvm_para.h new file mode 100644 index 000..14fab8f --- /dev/null +++ b/arch/frv/include/asm/kvm_para.h @@ -0,0 +1 @@ +#include asm-generic/kvm_para.h diff --git a/arch/h8300/include/asm/kvm_para.h
[PATCH 4/4 V16] Add check for suspended vm in softlockup detector
A suspended VM can cause spurious soft lockup warnings. To avoid these, the
watchdog now checks if the kernel knows it was stopped by the host and skips
the warning if so. When the watchdog is reset successfully, clear the guest
paused flag.
Signed-off-by: Eric B Munson emun...@mgebm.net
Cc: mi...@redhat.com
Cc: h...@zytor.com
Cc: ry...@linux.vnet.ibm.com
Cc: aligu...@us.ibm.com
Cc: mtosa...@redhat.com
Cc: kvm@vger.kernel.org
Cc: linux-a...@vger.kernel.org
Cc: x...@kernel.org
Cc: linux-ker...@vger.kernel.org
---
Changes from V3:
Clear the PAUSED flag when the watchdog is reset
kernel/watchdog.c | 12
1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index d117262..f6ffdc2 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -25,6 +25,7 @@
#include linux/sysctl.h
#include asm/irq_regs.h
+#include linux/kvm_para.h
#include linux/perf_event.h
int watchdog_enabled = 1;
@@ -280,6 +281,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct
hrtimer *hrtimer)
__this_cpu_write(softlockup_touch_sync, false);
sched_clock_tick();
}
+
+ /* Clear the guest paused flag on watchdog reset */
+ kvm_check_and_clear_guest_paused();
__touch_watchdog();
return HRTIMER_RESTART;
}
@@ -292,6 +296,14 @@ static enum hrtimer_restart watchdog_timer_fn(struct
hrtimer *hrtimer)
*/
duration = is_softlockup(touch_ts);
if (unlikely(duration)) {
+ /*
+* If a virtual machine is stopped by the host it can look to
+* the watchdog like a soft lockup, check to see if the host
+* stopped the vm before we issue the warning
+*/
+ if (kvm_check_and_clear_guest_paused())
+ return HRTIMER_RESTART;
+
/* only warn once */
if (__this_cpu_read(soft_watchdog_warn) == true)
return HRTIMER_RESTART;
--
1.7.5.4
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Re: [PATCH 0/4 V13] Avoid soft lockup message when KVM is stopped by host
On Mon, 05 Mar 2012, Marcelo Tosatti wrote: On Tue, Feb 14, 2012 at 04:17:20PM -0500, Eric B Munson wrote: On Tue, 14 Feb 2012, Marcelo Tosatti wrote: On Tue, Feb 14, 2012 at 10:50:13AM -0500, Eric B Munson wrote: On Tue, 14 Feb 2012, Marcelo Tosatti wrote: On Tue, Feb 14, 2012 at 10:29:31AM -0500, Eric B Munson wrote: On Wed, 08 Feb 2012, Eric B Munson wrote: When a guest kernel is stopped by the host hypervisor it can look like a soft lockup to the guest kernel. This false warning can mask later soft lockup warnings which may be real. This patch series adds a method for a host hypervisor to communicate to a guest kernel that it is being stopped. The final patch in the series has the watchdog check this flag when it goes to issue a soft lockup warning and skip the warning if the guest knows it was stopped. It was attempted to solve this in Qemu, but the side effects of saving and restoring the clock and tsc for each vcpu put the wall clock of the guest behind by the amount of time of the pause. This forces a guest to have ntp running in order to keep the wall clock accurate. Avi, Is this set fit for merging or is there something else you want changed? Eric, On Message-ID: 20120210160536.ga23...@amt.cnet, i asked: How is the stub getting included for other architectures again? Marcelo, Sorry, I put out V13 to answer that. There is a stub in asm-generic that was lost in the V11-V12 rebase. This stub has be included in the V13 set. Eric Eric, I know the stub has been included in the series. But i am asking how it is #include'ed for other architectures? (can't see that). Marcelo, kernel/watchdog.c now includes linux/kvm_para.h which includes asm/kvm_para.h. The check_and_clear function is defined in arch include/asm/kvm_para.h or in asm-generic/kvm_para.h for any arch lacking the specific header in their asm include dir. If I have misunderstood how these headers work, please let me know and I will fix it. There is no automatic inclusion of asm-generic/ headers. You must create kvm_para.h in each architecture's include/asm/ directory, #including asm-generic/kvm_para.h. Hopefully V16 handles this properly, please let me know if there is anything that needs to be addressed. I'd like to see this set in for the 3.4 window. Eric signature.asc Description: Digital signature
Re: native kvm tool hrtimer problem
On 03/08/2012 11:51 PM, Cyrill Gorcunov wrote: On Thu, Mar 08, 2012 at 04:31:17PM +0100, Daniele Carollo wrote: I don't really use the tap interface so lets CC Asias. Which guest kernel are you using, btw? Yup, Asias was using it, if my memory doesn't betray me. Also both -- host and guest kernel versions might be useful to know. iirc we were emulating rtc only while anything else passes through to kvm kernel driver. Cyrill As guest I'm using debian 6.0 squeeze found here http://people.debian.org/~aurel32/qemu/i386/debian_squeeze_i386_standard.qcow2 while on the host I'm using Opensuse 11.2 with kernel 3.3.0-rc1KVM gitted from here http://git.kernel.org/pub/scm/virt/kvm/kvm.git OK, lets see what Asias say. Hi, Daniele The guest should be fine, I use that image as well. Can you post the command line which you started the kvm tool? Is tap/virtio or vhost/virtio working before the iperf stress testing, like ping guestA in guesgB? Can you try it on host with stock kernel from your distro? -- Asias He -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
