[Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Paolo Bonzini]

The pvpanic mess is even bigger than anticipated.  Let's fix the monitor's
behavior (patch 1), get rid of all traces that the broken pvpanic existed
(patch 2), and give it a new name so that libvirt can detect a design
that works (patch 3).

All downstreams are urged to apply patches 1+2 as soon as they are
merged in QEMU.

Still, there are still other problems to solve.

In QEMU, exposing "-device isa-pvpanic" in the ACPI tables.  Quite frankly
I don't have the time to fix this.  We have ~3 months though.  Patch 3
should not be applied until it is fixed.

Also, libvirt needs to know under which circumstances to add "-device
isa-pvpanic", besides obviously the availability of the device.

IMHO it is just too complicated to retrofit all complications in
<on_crash>.  In fact, I suspect <on_crash> would match more closely QEMU's
"internal error" state, and it would be quite useful to add that to the
QEMU driver.

Thus, libvirt could add support for an <on_panic> element with the
following values:

- default, which depends on the hypervisor and is "crash" for Xen,
  "ignore" for everything else

- "crash", which is the only supported value on Xen and means "use
  the value of <on_crash>"

- ignore, which is the behavior of old libvirt that don't know pvpanic

- restart, destroy, preserve, rename-restart as for <on_crash>.  In
  particular, preserve can still use the crashed_guest_panicked status,
  thus keeping the API compatible.

- pause, to pause the VM (with a new substatus)

<on_panic> would also have a coredump='yes/no' attribute, where yes
is only valid if the element is *not* one of default/crash/ignore.
Only "default" and "ignore" would be accepted for QEMU that does not
support the isa-pvpanic device.

Ideally, the coredump attribute would be added to <on_crash> too
for simplicity (Xen would refuse coredump + rename-restart and
coredump + preserve).

Paolo


Paolo Bonzini (3):
  vl: allow "cont" from panicked state
  pc: get rid of builtin pvpanic
  pvpanic: rename to isa-pvpanic

 gdbstub.c            |  3 ---
 hw/i386/pc_piix.c    |  8 --------
 hw/i386/pc_q35.c     |  6 ------
 hw/misc/pvpanic.c    | 16 +++-------------
 include/hw/i386/pc.h |  3 ---
 vl.c                 |  6 ++----
 6 files changed, 5 insertions(+), 37 deletions(-)

-- 
1.8.3.1

[Qemu-devel] [PATCH 1/3] vl: allow "cont" from panicked state

[Paolo Bonzini]

After reporting the GUEST_PANICKED monitor event, QEMU stops the VM.
The reason for this is that events are edge-triggered, and can be lost if
management dies at the wrong time.  Stopping a panicked VM lets management
know of a panic even if it has crashed; management can learn about the
panic when it restarts and queries running QEMU processes.  The downside
is of course that the VM will be paused while management is not running,
but that is acceptable if it only happens with explicit "-device pvpanic".

Upon learning of a panic, management (if configured to do so) can pick a
variety of behaviors: leave the VM paused, reset it, destroy it.  In
addition to all of these behaviors, it is possible to dump the VM core
from the host.

However, right now, the panicked state is irreversible, and can only be
exited by resetting the machine.  This means that any policy decision
is entirely in the hands of the host.  In particular there is no way to
use the "reboot on panic" option together with pvpanic.

This patch makes the panicked state reversible (and removes various
workarounds that were there because of the state being irreversible).
With this change, management has a wider set of possible policies: it
can just log the crash and leave policy to the guest, it can leave the
VM paused.  In particular, the "log the crash and continue" is implemented
simply by sending a "cont" as soon as management learns about the panic.
Management could also implement the "irreversible paused state" itself.
And again, all such actions can be coupled with dumping the VM core.

Unfortunately we cannot change the behavior of 1.6.0.  Thus, even if
it uses "-device pvpanic", management should check for "cont" failures.
If "cont" fails, management can then log that the VM remained paused
and urge the administrator to update QEMU.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 gdbstub.c | 3 ---
 vl.c      | 6 ++----
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/gdbstub.c b/gdbstub.c
index 35ca7c2..747e67d 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -372,9 +372,6 @@ static inline void gdb_continue(GDBState *s)
 #ifdef CONFIG_USER_ONLY
     s->running_state = 1;
 #else
-    if (runstate_check(RUN_STATE_GUEST_PANICKED)) {
-        runstate_set(RUN_STATE_DEBUG);
-    }
     if (!runstate_needs_reset()) {
         vm_start();
     }
diff --git a/vl.c b/vl.c
index 25b8f2f..818d99e 100644
--- a/vl.c
+++ b/vl.c
@@ -637,9 +637,8 @@ static const RunStateTransition runstate_transitions_def[] = {
     { RUN_STATE_WATCHDOG, RUN_STATE_RUNNING },
     { RUN_STATE_WATCHDOG, RUN_STATE_FINISH_MIGRATE },
 
-    { RUN_STATE_GUEST_PANICKED, RUN_STATE_PAUSED },
+    { RUN_STATE_GUEST_PANICKED, RUN_STATE_RUNNING },
     { RUN_STATE_GUEST_PANICKED, RUN_STATE_FINISH_MIGRATE },
-    { RUN_STATE_GUEST_PANICKED, RUN_STATE_DEBUG },
 
     { RUN_STATE_MAX, RUN_STATE_MAX },
 };
@@ -685,8 +684,7 @@ int runstate_is_running(void)
 bool runstate_needs_reset(void)
 {
     return runstate_check(RUN_STATE_INTERNAL_ERROR) ||
-        runstate_check(RUN_STATE_SHUTDOWN) ||
-        runstate_check(RUN_STATE_GUEST_PANICKED);
+        runstate_check(RUN_STATE_SHUTDOWN);
 }
 
 StatusInfo *qmp_query_status(Error **errp)
-- 
1.8.3.1

[Qemu-devel] [PATCH 2/3] pc: get rid of builtin pvpanic

[Paolo Bonzini]

It is a source of pain, and the previous patch anyway changed the
behavior of "-M pc-1.5" compared to the real 1.5.

This also makes it clear that "-device pvpanic" is not enough:
it will not expose pvpanic in fw_cfg properly.

No idea how to fix that.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/i386/pc_piix.c    |  8 --------
 hw/i386/pc_q35.c     |  6 ------
 hw/misc/pvpanic.c    | 14 ++------------
 include/hw/i386/pc.h |  3 ---
 4 files changed, 2 insertions(+), 29 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index b58c255..b80f9a3 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -56,7 +56,6 @@ static const int ide_iobase[MAX_IDE_BUS] = { 0x1f0, 0x170 };
 static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, 0x376 };
 static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
 
-static bool has_pvpanic = true;
 static bool has_pci_info = true;
 
 /* PC hardware initialisation */
@@ -240,10 +239,6 @@ static void pc_init1(MemoryRegion *system_memory,
     if (pci_enabled) {
         pc_pci_device_init(pci_bus);
     }
-
-    if (has_pvpanic) {
-        pvpanic_init(isa_bus);
-    }
 }
 
 static void pc_init_pci(QEMUMachineInitArgs *args)
@@ -269,7 +264,6 @@ static void pc_init_pci_1_5(QEMUMachineInitArgs *args)
 
 static void pc_init_pci_1_4(QEMUMachineInitArgs *args)
 {
-    has_pvpanic = false;
     x86_cpu_compat_set_features("n270", FEAT_1_ECX, 0, CPUID_EXT_MOVBE);
     pc_init_pci_1_5(args);
 }
@@ -302,7 +296,6 @@ static void pc_init_pci_no_kvmclock(QEMUMachineInitArgs *args)
     const char *kernel_cmdline = args->kernel_cmdline;
     const char *initrd_filename = args->initrd_filename;
     const char *boot_device = args->boot_device;
-    has_pvpanic = false;
     has_pci_info = false;
     disable_kvm_pv_eoi();
     enable_compat_apic_id_mode();
@@ -321,7 +314,6 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
     const char *kernel_cmdline = args->kernel_cmdline;
     const char *initrd_filename = args->initrd_filename;
     const char *boot_device = args->boot_device;
-    has_pvpanic = false;
     has_pci_info = false;
     if (cpu_model == NULL)
         cpu_model = "486";
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 0b1d2e3..fb403b8 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -46,7 +46,6 @@
 /* ICH9 AHCI has 6 ports */
 #define MAX_SATA_PORTS     6
 
-static bool has_pvpanic = true;
 static bool has_pci_info = true;
 
 /* PC hardware initialisation */
@@ -210,10 +209,6 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
     if (pci_enabled) {
         pc_pci_device_init(host_bus);
     }
-
-    if (has_pvpanic) {
-        pvpanic_init(isa_bus);
-    }
 }
 
 static void pc_q35_init_1_5(QEMUMachineInitArgs *args)
@@ -224,7 +219,6 @@ static void pc_q35_init_1_5(QEMUMachineInitArgs *args)
 
 static void pc_q35_init_1_4(QEMUMachineInitArgs *args)
 {
-    has_pvpanic = false;
     x86_cpu_compat_set_features("n270", FEAT_1_ECX, 0, CPUID_EXT_MOVBE);
     pc_q35_init_1_5(args);
 }
diff --git a/hw/misc/pvpanic.c b/hw/misc/pvpanic.c
index 7bb49a5..1928cc9 100644
--- a/hw/misc/pvpanic.c
+++ b/hw/misc/pvpanic.c
@@ -101,7 +101,8 @@ static void pvpanic_isa_realizefn(DeviceState *dev, Error **errp)
     isa_register_ioport(d, &s->io, s->ioport);
 }
 
-static void pvpanic_fw_cfg(ISADevice *dev, FWCfgState *fw_cfg)
+static void __attribute__((unused)) pvpanic_fw_cfg(ISADevice *dev,
+                                                   FWCfgState *fw_cfg)
 {
     PVPanicState *s = ISA_PVPANIC_DEVICE(dev);
     uint16_t *pvpanic_port = g_malloc(sizeof(*pvpanic_port));
@@ -111,17 +112,6 @@ static void pvpanic_fw_cfg(ISADevice *dev, FWCfgState *fw_cfg)
                     sizeof(*pvpanic_port));
 }
 
-void pvpanic_init(ISABus *bus)
-{
-    ISADevice *dev;
-    FWCfgState *fw_cfg = fw_cfg_find();
-    if (!fw_cfg) {
-        return;
-    }
-    dev = isa_create_simple (bus, TYPE_ISA_PVPANIC_DEVICE);
-    pvpanic_fw_cfg(dev, fw_cfg);
-}
-
 static Property pvpanic_isa_properties[] = {
     DEFINE_PROP_UINT16("ioport", PVPanicState, ioport, 0x505),
     DEFINE_PROP_END_OF_LIST(),
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 7fb97b0..064cc81 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -194,9 +194,6 @@ static inline bool isa_ne2000_init(ISABus *bus, int base, int irq, NICInfo *nd)
 /* pc_sysfw.c */
 void pc_system_firmware_init(MemoryRegion *rom_memory);
 
-/* pvpanic.c */
-void pvpanic_init(ISABus *bus);
-
 /* e820 types */
 #define E820_RAM        1
 #define E820_RESERVED   2
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH 2/3] pc: get rid of builtin pvpanic

[Michael S. Tsirkin]

On Wed, Aug 21, 2013 at 06:43:15PM +0200, Paolo Bonzini wrote:
> It is a source of pain, and the previous patch anyway changed the
> behavior of "-M pc-1.5" compared to the real 1.5.
> 
> This also makes it clear that "-device pvpanic" is not enough:
> it will not expose pvpanic in fw_cfg properly.
> 
> No idea how to fix that.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

That should be the first step. Make the device work properly.
We'll discuss compatibility when that is clear.

> ---
>  hw/i386/pc_piix.c    |  8 --------
>  hw/i386/pc_q35.c     |  6 ------
>  hw/misc/pvpanic.c    | 14 ++------------
>  include/hw/i386/pc.h |  3 ---
>  4 files changed, 2 insertions(+), 29 deletions(-)
> 
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index b58c255..b80f9a3 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -56,7 +56,6 @@ static const int ide_iobase[MAX_IDE_BUS] = { 0x1f0, 0x170 };
>  static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, 0x376 };
>  static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
>  
> -static bool has_pvpanic = true;
>  static bool has_pci_info = true;
>  
>  /* PC hardware initialisation */
> @@ -240,10 +239,6 @@ static void pc_init1(MemoryRegion *system_memory,
>      if (pci_enabled) {
>          pc_pci_device_init(pci_bus);
>      }
> -
> -    if (has_pvpanic) {
> -        pvpanic_init(isa_bus);
> -    }
>  }
>  
>  static void pc_init_pci(QEMUMachineInitArgs *args)
> @@ -269,7 +264,6 @@ static void pc_init_pci_1_5(QEMUMachineInitArgs *args)
>  
>  static void pc_init_pci_1_4(QEMUMachineInitArgs *args)
>  {
> -    has_pvpanic = false;
>      x86_cpu_compat_set_features("n270", FEAT_1_ECX, 0, CPUID_EXT_MOVBE);
>      pc_init_pci_1_5(args);
>  }
> @@ -302,7 +296,6 @@ static void pc_init_pci_no_kvmclock(QEMUMachineInitArgs *args)
>      const char *kernel_cmdline = args->kernel_cmdline;
>      const char *initrd_filename = args->initrd_filename;
>      const char *boot_device = args->boot_device;
> -    has_pvpanic = false;
>      has_pci_info = false;
>      disable_kvm_pv_eoi();
>      enable_compat_apic_id_mode();
> @@ -321,7 +314,6 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
>      const char *kernel_cmdline = args->kernel_cmdline;
>      const char *initrd_filename = args->initrd_filename;
>      const char *boot_device = args->boot_device;
> -    has_pvpanic = false;
>      has_pci_info = false;
>      if (cpu_model == NULL)
>          cpu_model = "486";
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 0b1d2e3..fb403b8 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -46,7 +46,6 @@
>  /* ICH9 AHCI has 6 ports */
>  #define MAX_SATA_PORTS     6
>  
> -static bool has_pvpanic = true;
>  static bool has_pci_info = true;
>  
>  /* PC hardware initialisation */
> @@ -210,10 +209,6 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
>      if (pci_enabled) {
>          pc_pci_device_init(host_bus);
>      }
> -
> -    if (has_pvpanic) {
> -        pvpanic_init(isa_bus);
> -    }
>  }
>  
>  static void pc_q35_init_1_5(QEMUMachineInitArgs *args)
> @@ -224,7 +219,6 @@ static void pc_q35_init_1_5(QEMUMachineInitArgs *args)
>  
>  static void pc_q35_init_1_4(QEMUMachineInitArgs *args)
>  {
> -    has_pvpanic = false;
>      x86_cpu_compat_set_features("n270", FEAT_1_ECX, 0, CPUID_EXT_MOVBE);
>      pc_q35_init_1_5(args);
>  }
> diff --git a/hw/misc/pvpanic.c b/hw/misc/pvpanic.c
> index 7bb49a5..1928cc9 100644
> --- a/hw/misc/pvpanic.c
> +++ b/hw/misc/pvpanic.c
> @@ -101,7 +101,8 @@ static void pvpanic_isa_realizefn(DeviceState *dev, Error **errp)
>      isa_register_ioport(d, &s->io, s->ioport);
>  }
>  
> -static void pvpanic_fw_cfg(ISADevice *dev, FWCfgState *fw_cfg)
> +static void __attribute__((unused)) pvpanic_fw_cfg(ISADevice *dev,
> +                                                   FWCfgState *fw_cfg)
>  {
>      PVPanicState *s = ISA_PVPANIC_DEVICE(dev);
>      uint16_t *pvpanic_port = g_malloc(sizeof(*pvpanic_port));
> @@ -111,17 +112,6 @@ static void pvpanic_fw_cfg(ISADevice *dev, FWCfgState *fw_cfg)
>                      sizeof(*pvpanic_port));
>  }
>  
> -void pvpanic_init(ISABus *bus)
> -{
> -    ISADevice *dev;
> -    FWCfgState *fw_cfg = fw_cfg_find();
> -    if (!fw_cfg) {
> -        return;
> -    }
> -    dev = isa_create_simple (bus, TYPE_ISA_PVPANIC_DEVICE);
> -    pvpanic_fw_cfg(dev, fw_cfg);
> -}
> -
>  static Property pvpanic_isa_properties[] = {
>      DEFINE_PROP_UINT16("ioport", PVPanicState, ioport, 0x505),
>      DEFINE_PROP_END_OF_LIST(),
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 7fb97b0..064cc81 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -194,9 +194,6 @@ static inline bool isa_ne2000_init(ISABus *bus, int base, int irq, NICInfo *nd)
>  /* pc_sysfw.c */
>  void pc_system_firmware_init(MemoryRegion *rom_memory);
>  
> -/* pvpanic.c */
> -void pvpanic_init(ISABus *bus);
> -
>  /* e820 types */
>  #define E820_RAM        1
>  #define E820_RESERVED   2
> -- 
> 1.8.3.1
> 

Re: [Qemu-devel] [PATCH 2/3] pc: get rid of builtin pvpanic

[Paolo Bonzini]

Il 21/08/2013 19:03, Michael S. Tsirkin ha scritto:
>> > It is a source of pain, and the previous patch anyway changed the
>> > behavior of "-M pc-1.5" compared to the real 1.5.
>> > 
>> > This also makes it clear that "-device pvpanic" is not enough:
>> > it will not expose pvpanic in fw_cfg properly.
>> > 
>> > No idea how to fix that.
>> > 
>> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> That should be the first step. Make the device work properly.
> We'll discuss compatibility when that is clear.
> 

Actually these patches are not based on origin/master (my mistake)... I
haven't tested, rebasing should be enough if "-device pvpanic" was
tested properly for 1.6.

Paolo

Re: [Qemu-devel] [PATCH 2/3] pc: get rid of builtin pvpanic

[Andreas Färber]

Am 21.08.2013 19:02, schrieb Paolo Bonzini:
> Il 21/08/2013 19:03, Michael S. Tsirkin ha scritto:
>>>> It is a source of pain, and the previous patch anyway changed the
>>>> behavior of "-M pc-1.5" compared to the real 1.5.
>>>>
>>>> This also makes it clear that "-device pvpanic" is not enough:
>>>> it will not expose pvpanic in fw_cfg properly.
>>>>
>>>> No idea how to fix that.
>>>>
>>>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> That should be the first step. Make the device work properly.
>> We'll discuss compatibility when that is clear.
>>
> 
> Actually these patches are not based on origin/master (my mistake)... I
> haven't tested, rebasing should be enough if "-device pvpanic" was
> tested properly for 1.6.

I haven't tested myself but I remember seeing patches moving fw_cfg
integration into the initfn/realizefn.

Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

Re: [Qemu-devel] [PATCH 2/3] pc: get rid of builtin pvpanic

[Michael S. Tsirkin]

On Wed, Aug 21, 2013 at 08:03:58PM +0300, Michael S. Tsirkin wrote:
> On Wed, Aug 21, 2013 at 06:43:15PM +0200, Paolo Bonzini wrote:
> > It is a source of pain, and the previous patch anyway changed the
> > behavior of "-M pc-1.5" compared to the real 1.5.
> > 
> > This also makes it clear that "-device pvpanic" is not enough:
> > it will not expose pvpanic in fw_cfg properly.
> > 
> > No idea how to fix that.
> > 
> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> 
> That should be the first step. Make the device work properly.
> We'll discuss compatibility when that is clear.

So not nacking yet but I think it's too early to apply.

> > ---
> >  hw/i386/pc_piix.c    |  8 --------
> >  hw/i386/pc_q35.c     |  6 ------
> >  hw/misc/pvpanic.c    | 14 ++------------
> >  include/hw/i386/pc.h |  3 ---
> >  4 files changed, 2 insertions(+), 29 deletions(-)
> > 
> > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > index b58c255..b80f9a3 100644
> > --- a/hw/i386/pc_piix.c
> > +++ b/hw/i386/pc_piix.c
> > @@ -56,7 +56,6 @@ static const int ide_iobase[MAX_IDE_BUS] = { 0x1f0, 0x170 };
> >  static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, 0x376 };
> >  static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
> >  
> > -static bool has_pvpanic = true;
> >  static bool has_pci_info = true;
> >  
> >  /* PC hardware initialisation */
> > @@ -240,10 +239,6 @@ static void pc_init1(MemoryRegion *system_memory,
> >      if (pci_enabled) {
> >          pc_pci_device_init(pci_bus);
> >      }
> > -
> > -    if (has_pvpanic) {
> > -        pvpanic_init(isa_bus);
> > -    }
> >  }
> >  
> >  static void pc_init_pci(QEMUMachineInitArgs *args)
> > @@ -269,7 +264,6 @@ static void pc_init_pci_1_5(QEMUMachineInitArgs *args)
> >  
> >  static void pc_init_pci_1_4(QEMUMachineInitArgs *args)
> >  {
> > -    has_pvpanic = false;
> >      x86_cpu_compat_set_features("n270", FEAT_1_ECX, 0, CPUID_EXT_MOVBE);
> >      pc_init_pci_1_5(args);
> >  }
> > @@ -302,7 +296,6 @@ static void pc_init_pci_no_kvmclock(QEMUMachineInitArgs *args)
> >      const char *kernel_cmdline = args->kernel_cmdline;
> >      const char *initrd_filename = args->initrd_filename;
> >      const char *boot_device = args->boot_device;
> > -    has_pvpanic = false;
> >      has_pci_info = false;
> >      disable_kvm_pv_eoi();
> >      enable_compat_apic_id_mode();
> > @@ -321,7 +314,6 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
> >      const char *kernel_cmdline = args->kernel_cmdline;
> >      const char *initrd_filename = args->initrd_filename;
> >      const char *boot_device = args->boot_device;
> > -    has_pvpanic = false;
> >      has_pci_info = false;
> >      if (cpu_model == NULL)
> >          cpu_model = "486";
> > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> > index 0b1d2e3..fb403b8 100644
> > --- a/hw/i386/pc_q35.c
> > +++ b/hw/i386/pc_q35.c
> > @@ -46,7 +46,6 @@
> >  /* ICH9 AHCI has 6 ports */
> >  #define MAX_SATA_PORTS     6
> >  
> > -static bool has_pvpanic = true;
> >  static bool has_pci_info = true;
> >  
> >  /* PC hardware initialisation */
> > @@ -210,10 +209,6 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
> >      if (pci_enabled) {
> >          pc_pci_device_init(host_bus);
> >      }
> > -
> > -    if (has_pvpanic) {
> > -        pvpanic_init(isa_bus);
> > -    }
> >  }
> >  
> >  static void pc_q35_init_1_5(QEMUMachineInitArgs *args)
> > @@ -224,7 +219,6 @@ static void pc_q35_init_1_5(QEMUMachineInitArgs *args)
> >  
> >  static void pc_q35_init_1_4(QEMUMachineInitArgs *args)
> >  {
> > -    has_pvpanic = false;
> >      x86_cpu_compat_set_features("n270", FEAT_1_ECX, 0, CPUID_EXT_MOVBE);
> >      pc_q35_init_1_5(args);
> >  }
> > diff --git a/hw/misc/pvpanic.c b/hw/misc/pvpanic.c
> > index 7bb49a5..1928cc9 100644
> > --- a/hw/misc/pvpanic.c
> > +++ b/hw/misc/pvpanic.c
> > @@ -101,7 +101,8 @@ static void pvpanic_isa_realizefn(DeviceState *dev, Error **errp)
> >      isa_register_ioport(d, &s->io, s->ioport);
> >  }
> >  
> > -static void pvpanic_fw_cfg(ISADevice *dev, FWCfgState *fw_cfg)
> > +static void __attribute__((unused)) pvpanic_fw_cfg(ISADevice *dev,
> > +                                                   FWCfgState *fw_cfg)
> >  {
> >      PVPanicState *s = ISA_PVPANIC_DEVICE(dev);
> >      uint16_t *pvpanic_port = g_malloc(sizeof(*pvpanic_port));
> > @@ -111,17 +112,6 @@ static void pvpanic_fw_cfg(ISADevice *dev, FWCfgState *fw_cfg)
> >                      sizeof(*pvpanic_port));
> >  }
> >  
> > -void pvpanic_init(ISABus *bus)
> > -{
> > -    ISADevice *dev;
> > -    FWCfgState *fw_cfg = fw_cfg_find();
> > -    if (!fw_cfg) {
> > -        return;
> > -    }
> > -    dev = isa_create_simple (bus, TYPE_ISA_PVPANIC_DEVICE);
> > -    pvpanic_fw_cfg(dev, fw_cfg);
> > -}
> > -
> >  static Property pvpanic_isa_properties[] = {
> >      DEFINE_PROP_UINT16("ioport", PVPanicState, ioport, 0x505),
> >      DEFINE_PROP_END_OF_LIST(),
> > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> > index 7fb97b0..064cc81 100644
> > --- a/include/hw/i386/pc.h
> > +++ b/include/hw/i386/pc.h
> > @@ -194,9 +194,6 @@ static inline bool isa_ne2000_init(ISABus *bus, int base, int irq, NICInfo *nd)
> >  /* pc_sysfw.c */
> >  void pc_system_firmware_init(MemoryRegion *rom_memory);
> >  
> > -/* pvpanic.c */
> > -void pvpanic_init(ISABus *bus);
> > -
> >  /* e820 types */
> >  #define E820_RAM        1
> >  #define E820_RESERVED   2
> > -- 
> > 1.8.3.1
> > 

Re: [Qemu-devel] [PATCH 2/3] pc: get rid of builtin pvpanic

[Michael S. Tsirkin]

On Wed, Aug 21, 2013 at 06:43:15PM +0200, Paolo Bonzini wrote:
> It is a source of pain, and the previous patch anyway changed the
> behavior of "-M pc-1.5" compared to the real 1.5.
> 
> This also makes it clear that "-device pvpanic" is not enough:
> it will not expose pvpanic in fw_cfg properly.
> 
> No idea how to fix that.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Re: fixing that. I should stop arguing on the mailing
list and post latest version of the ACPI generation patchset :).
Once there we won't need a FW CFG entry anymore.

> ---
>  hw/i386/pc_piix.c    |  8 --------
>  hw/i386/pc_q35.c     |  6 ------
>  hw/misc/pvpanic.c    | 14 ++------------
>  include/hw/i386/pc.h |  3 ---
>  4 files changed, 2 insertions(+), 29 deletions(-)
> 
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index b58c255..b80f9a3 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -56,7 +56,6 @@ static const int ide_iobase[MAX_IDE_BUS] = { 0x1f0, 0x170 };
>  static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, 0x376 };
>  static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
>  
> -static bool has_pvpanic = true;
>  static bool has_pci_info = true;
>  
>  /* PC hardware initialisation */
> @@ -240,10 +239,6 @@ static void pc_init1(MemoryRegion *system_memory,
>      if (pci_enabled) {
>          pc_pci_device_init(pci_bus);
>      }
> -
> -    if (has_pvpanic) {
> -        pvpanic_init(isa_bus);
> -    }
>  }
>  
>  static void pc_init_pci(QEMUMachineInitArgs *args)
> @@ -269,7 +264,6 @@ static void pc_init_pci_1_5(QEMUMachineInitArgs *args)
>  
>  static void pc_init_pci_1_4(QEMUMachineInitArgs *args)
>  {
> -    has_pvpanic = false;
>      x86_cpu_compat_set_features("n270", FEAT_1_ECX, 0, CPUID_EXT_MOVBE);
>      pc_init_pci_1_5(args);
>  }
> @@ -302,7 +296,6 @@ static void pc_init_pci_no_kvmclock(QEMUMachineInitArgs *args)
>      const char *kernel_cmdline = args->kernel_cmdline;
>      const char *initrd_filename = args->initrd_filename;
>      const char *boot_device = args->boot_device;
> -    has_pvpanic = false;
>      has_pci_info = false;
>      disable_kvm_pv_eoi();
>      enable_compat_apic_id_mode();
> @@ -321,7 +314,6 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
>      const char *kernel_cmdline = args->kernel_cmdline;
>      const char *initrd_filename = args->initrd_filename;
>      const char *boot_device = args->boot_device;
> -    has_pvpanic = false;
>      has_pci_info = false;
>      if (cpu_model == NULL)
>          cpu_model = "486";
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 0b1d2e3..fb403b8 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -46,7 +46,6 @@
>  /* ICH9 AHCI has 6 ports */
>  #define MAX_SATA_PORTS     6
>  
> -static bool has_pvpanic = true;
>  static bool has_pci_info = true;
>  
>  /* PC hardware initialisation */
> @@ -210,10 +209,6 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
>      if (pci_enabled) {
>          pc_pci_device_init(host_bus);
>      }
> -
> -    if (has_pvpanic) {
> -        pvpanic_init(isa_bus);
> -    }
>  }
>  
>  static void pc_q35_init_1_5(QEMUMachineInitArgs *args)
> @@ -224,7 +219,6 @@ static void pc_q35_init_1_5(QEMUMachineInitArgs *args)
>  
>  static void pc_q35_init_1_4(QEMUMachineInitArgs *args)
>  {
> -    has_pvpanic = false;
>      x86_cpu_compat_set_features("n270", FEAT_1_ECX, 0, CPUID_EXT_MOVBE);
>      pc_q35_init_1_5(args);
>  }
> diff --git a/hw/misc/pvpanic.c b/hw/misc/pvpanic.c
> index 7bb49a5..1928cc9 100644
> --- a/hw/misc/pvpanic.c
> +++ b/hw/misc/pvpanic.c
> @@ -101,7 +101,8 @@ static void pvpanic_isa_realizefn(DeviceState *dev, Error **errp)
>      isa_register_ioport(d, &s->io, s->ioport);
>  }
>  
> -static void pvpanic_fw_cfg(ISADevice *dev, FWCfgState *fw_cfg)
> +static void __attribute__((unused)) pvpanic_fw_cfg(ISADevice *dev,
> +                                                   FWCfgState *fw_cfg)
>  {
>      PVPanicState *s = ISA_PVPANIC_DEVICE(dev);
>      uint16_t *pvpanic_port = g_malloc(sizeof(*pvpanic_port));
> @@ -111,17 +112,6 @@ static void pvpanic_fw_cfg(ISADevice *dev, FWCfgState *fw_cfg)
>                      sizeof(*pvpanic_port));
>  }
>  
> -void pvpanic_init(ISABus *bus)
> -{
> -    ISADevice *dev;
> -    FWCfgState *fw_cfg = fw_cfg_find();
> -    if (!fw_cfg) {
> -        return;
> -    }
> -    dev = isa_create_simple (bus, TYPE_ISA_PVPANIC_DEVICE);
> -    pvpanic_fw_cfg(dev, fw_cfg);
> -}
> -
>  static Property pvpanic_isa_properties[] = {
>      DEFINE_PROP_UINT16("ioport", PVPanicState, ioport, 0x505),
>      DEFINE_PROP_END_OF_LIST(),
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 7fb97b0..064cc81 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -194,9 +194,6 @@ static inline bool isa_ne2000_init(ISABus *bus, int base, int irq, NICInfo *nd)
>  /* pc_sysfw.c */
>  void pc_system_firmware_init(MemoryRegion *rom_memory);
>  
> -/* pvpanic.c */
> -void pvpanic_init(ISABus *bus);
> -
>  /* e820 types */
>  #define E820_RAM        1
>  #define E820_RESERVED   2
> -- 
> 1.8.3.1
> 

[Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Paolo Bonzini]

The pvpanic situation is already messed up enough.  Let us give our
libvirt friends an easy indication that we have untied our side.

Not-yet-signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
... because we first have to determine how to expose the device's existence
    in the ACPI tables or in fw_cfg.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/misc/pvpanic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/misc/pvpanic.c b/hw/misc/pvpanic.c
index 1928cc9..b53011d 100644
--- a/hw/misc/pvpanic.c
+++ b/hw/misc/pvpanic.c
@@ -27,7 +27,7 @@
 /* The pv event value */
 #define PVPANIC_PANICKED        (1 << PVPANIC_F_PANICKED)
 
-#define TYPE_ISA_PVPANIC_DEVICE    "pvpanic"
+#define TYPE_ISA_PVPANIC_DEVICE    "isa-pvpanic"
 #define ISA_PVPANIC_DEVICE(obj)    \
     OBJECT_CHECK(PVPanicState, (obj), TYPE_ISA_PVPANIC_DEVICE)
 
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Michael S. Tsirkin]

On Wed, Aug 21, 2013 at 06:43:16PM +0200, Paolo Bonzini wrote:
> The pvpanic situation is already messed up enough.  Let us give our
> libvirt friends an easy indication that we have untied our side.
> 
> Not-yet-signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ... because we first have to determine how to expose the device's existence
>     in the ACPI tables or in fw_cfg.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

So it's isa-pvpanic meaning "I-am-sure-this-is-the-last-bug-pvpanic"

If we feel there's need to give libvirt a way to do
introspection into QEMU bugs, let's architect one.
Randomly renaming devices in the vain hope it's
the last major bug is not it.

NACK




> ---
>  hw/misc/pvpanic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/misc/pvpanic.c b/hw/misc/pvpanic.c
> index 1928cc9..b53011d 100644
> --- a/hw/misc/pvpanic.c
> +++ b/hw/misc/pvpanic.c
> @@ -27,7 +27,7 @@
>  /* The pv event value */
>  #define PVPANIC_PANICKED        (1 << PVPANIC_F_PANICKED)
>  
> -#define TYPE_ISA_PVPANIC_DEVICE    "pvpanic"
> +#define TYPE_ISA_PVPANIC_DEVICE    "isa-pvpanic"
>  #define ISA_PVPANIC_DEVICE(obj)    \
>      OBJECT_CHECK(PVPanicState, (obj), TYPE_ISA_PVPANIC_DEVICE)
>  
> -- 
> 1.8.3.1

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Paolo Bonzini]

Il 21/08/2013 19:01, Michael S. Tsirkin ha scritto:
>> > The pvpanic situation is already messed up enough.  Let us give our
>> > libvirt friends an easy indication that we have untied our side.
>> > 
>> > Not-yet-signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> > ... because we first have to determine how to expose the device's existence
>> >     in the ACPI tables or in fw_cfg.
>> > 
>> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> So it's isa-pvpanic meaning "I-am-sure-this-is-the-last-bug-pvpanic"

More like "we tested pvpanic for more than 2 weeks and did not find
anything that's utterly broken in the design".

And more practically "you are sure there are no traces of builtin
pvpanic; also, panicked state is reversible".

Paolo

> If we feel there's need to give libvirt a way to do
> introspection into QEMU bugs, let's architect one.
> Randomly renaming devices in the vain hope it's
> the last major bug is not it.

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Michael S. Tsirkin]

On Wed, Aug 21, 2013 at 07:01:39PM +0200, Paolo Bonzini wrote:
> Il 21/08/2013 19:01, Michael S. Tsirkin ha scritto:
> >> > The pvpanic situation is already messed up enough.  Let us give our
> >> > libvirt friends an easy indication that we have untied our side.
> >> > 
> >> > Not-yet-signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> >> > ... because we first have to determine how to expose the device's existence
> >> >     in the ACPI tables or in fw_cfg.
> >> > 
> >> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> > So it's isa-pvpanic meaning "I-am-sure-this-is-the-last-bug-pvpanic"
> 
> More like "we tested pvpanic for more than 2 weeks and did not find
> anything that's utterly broken in the design".
> 
> And more practically "you are sure there are no traces of builtin
> pvpanic; also, panicked state is reversible".
> 
> Paolo

isa-pvpanic does not look like a sane way to say that.

NACK

> > If we feel there's need to give libvirt a way to do
> > introspection into QEMU bugs, let's architect one.
> > Randomly renaming devices in the vain hope it's
> > the last major bug is not it.

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Paolo Bonzini]

Il 21/08/2013 19:07, Michael S. Tsirkin ha scritto:
> On Wed, Aug 21, 2013 at 07:01:39PM +0200, Paolo Bonzini wrote:
>> Il 21/08/2013 19:01, Michael S. Tsirkin ha scritto:
>>>>> The pvpanic situation is already messed up enough.  Let us give our
>>>>> libvirt friends an easy indication that we have untied our side.
>>>>>
>>>>> Not-yet-signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>>>>> ... because we first have to determine how to expose the device's existence
>>>>>     in the ACPI tables or in fw_cfg.
>>>>>
>>>>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>>> So it's isa-pvpanic meaning "I-am-sure-this-is-the-last-bug-pvpanic"
>>
>> More like "we tested pvpanic for more than 2 weeks and did not find
>> anything that's utterly broken in the design".
>>
>> And more practically "you are sure there are no traces of builtin
>> pvpanic; also, panicked state is reversible".
> 
> isa-pvpanic does not look like a sane way to say that.
> 
> NACK

You know that a single developer's NACK counts nothing (it can be you,
it can be me), don't you?

Paolo

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Michael S. Tsirkin]

On Wed, Aug 21, 2013 at 07:06:21PM +0200, Paolo Bonzini wrote:
> Il 21/08/2013 19:07, Michael S. Tsirkin ha scritto:
> > On Wed, Aug 21, 2013 at 07:01:39PM +0200, Paolo Bonzini wrote:
> >> Il 21/08/2013 19:01, Michael S. Tsirkin ha scritto:
> >>>>> The pvpanic situation is already messed up enough.  Let us give our
> >>>>> libvirt friends an easy indication that we have untied our side.
> >>>>>
> >>>>> Not-yet-signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> >>>>> ... because we first have to determine how to expose the device's existence
> >>>>>     in the ACPI tables or in fw_cfg.
> >>>>>
> >>>>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> >>> So it's isa-pvpanic meaning "I-am-sure-this-is-the-last-bug-pvpanic"
> >>
> >> More like "we tested pvpanic for more than 2 weeks and did not find
> >> anything that's utterly broken in the design".
> >>
> >> And more practically "you are sure there are no traces of builtin
> >> pvpanic; also, panicked state is reversible".
> > 
> > isa-pvpanic does not look like a sane way to say that.
> > 
> > NACK
> 
> You know that a single developer's NACK counts nothing (it can be you,
> it can be me), don't you?
> 
> Paolo

No I don't.

-- 
MST

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Laszlo Ersek]

On 08/21/13 19:06, Paolo Bonzini wrote:
> Il 21/08/2013 19:07, Michael S. Tsirkin ha scritto:

>> NACK
> 
> You know that a single developer's NACK counts nothing (it can be you,
> it can be me), don't you?

going meta...

What's this?

All I know (... I think I know) about patch acceptance is that Anthony
prefers to have at least one R-b. As far as I've seen this is not a hard
requirement (for example, maintainers sometimes send unreviewed patches
in a pull request, and on occasion they are merged).

No words have been spent on NAKs yet (... since my subscription, that
is). Is this stuff formalized somewhere?

Sorry for wasting time...

Thanks,
Laszlo

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Paolo Bonzini]

Il 22/08/2013 14:43, Laszlo Ersek ha scritto:
> On 08/21/13 19:06, Paolo Bonzini wrote:
>> Il 21/08/2013 19:07, Michael S. Tsirkin ha scritto:
> 
>>> NACK
>>
>> You know that a single developer's NACK counts nothing (it can be you,
>> it can be me), don't you?
> 
> going meta...
> 
> What's this?
> 
> All I know (... I think I know) about patch acceptance is that Anthony
> prefers to have at least one R-b. As far as I've seen this is not a hard
> requirement (for example, maintainers sometimes send unreviewed patches
> in a pull request, and on occasion they are merged).
> 
> No words have been spent on NAKs yet (... since my subscription, that
> is). Is this stuff formalized somewhere?
> 
> Sorry for wasting time...

No, it's not.  But for example I NACKed removal of pvpanic from 1.6, it
was overridden, and I didn't complain too much.

Paolo

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Michael S. Tsirkin]

On Thu, Aug 22, 2013 at 02:41:51PM +0200, Paolo Bonzini wrote:
> Il 22/08/2013 14:43, Laszlo Ersek ha scritto:
> > On 08/21/13 19:06, Paolo Bonzini wrote:
> >> Il 21/08/2013 19:07, Michael S. Tsirkin ha scritto:
> > 
> >>> NACK
> >>
> >> You know that a single developer's NACK counts nothing (it can be you,
> >> it can be me), don't you?
> > 
> > going meta...
> > 
> > What's this?
> > 
> > All I know (... I think I know) about patch acceptance is that Anthony
> > prefers to have at least one R-b. As far as I've seen this is not a hard
> > requirement (for example, maintainers sometimes send unreviewed patches
> > in a pull request, and on occasion they are merged).
> > 
> > No words have been spent on NAKs yet (... since my subscription, that
> > is). Is this stuff formalized somewhere?
> > 
> > Sorry for wasting time...
> 
> No, it's not.  But for example I NACKed removal of pvpanic from 1.6, it
> was overridden, and I didn't complain too much.
> 
> Paolo

I don't think it was overridden.

In fact you NACKed an explicit -device pvpanic.  You suggested disabling
in 1.6 but keeping it a builtin, but this was never implemented,
afterwards issues with Linux guests surfaced, we discussed this
again on the KVM call, and there seemed to be a
concensus that it's an OK patch, with some issues. A week later Marcel
sent v2, it worked and looked like the least problematic path to take.

-- 
MST

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Anthony Liguori]

Laszlo Ersek <lersek@redhat.com> writes:

> On 08/21/13 19:06, Paolo Bonzini wrote:
>> Il 21/08/2013 19:07, Michael S. Tsirkin ha scritto:
>
>>> NACK
>> 
>> You know that a single developer's NACK counts nothing (it can be you,
>> it can be me), don't you?
>
> going meta...
>
> What's this?
>
> All I know (... I think I know) about patch acceptance is that Anthony
> prefers to have at least one R-b. As far as I've seen this is not a hard
> requirement (for example, maintainers sometimes send unreviewed patches
> in a pull request, and on occasion they are merged).

I look very poorly on anyone nacking anything.  I value constructive
feedback.

Nacking does not add any value to the conversation.  I admire the fact
that we've been able to maintain a very high level of conversation over
the years on qemu-devel and throwing around nacks just lowers the
overall tone.

If you can't think of anything better to say than NACK, don't even
bother sending the email in the first place.

Regards,

Anthony Liguori

>
> No words have been spent on NAKs yet (... since my subscription, that
> is). Is this stuff formalized somewhere?
>
> Sorry for wasting time...
>
> Thanks,
> Laszlo

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Michael S. Tsirkin]

On Thu, Aug 22, 2013 at 11:50:43AM -0500, Anthony Liguori wrote:
> Laszlo Ersek <lersek@redhat.com> writes:
> 
> > On 08/21/13 19:06, Paolo Bonzini wrote:
> >> Il 21/08/2013 19:07, Michael S. Tsirkin ha scritto:
> >
> >>> NACK
> >> 
> >> You know that a single developer's NACK counts nothing (it can be you,
> >> it can be me), don't you?
> >
> > going meta...
> >
> > What's this?
> >
> > All I know (... I think I know) about patch acceptance is that Anthony
> > prefers to have at least one R-b. As far as I've seen this is not a hard
> > requirement (for example, maintainers sometimes send unreviewed patches
> > in a pull request, and on occasion they are merged).
> 
> I look very poorly on anyone nacking anything.  I value constructive
> feedback.
> Nacking does not add any value to the conversation.  I admire the fact
> that we've been able to maintain a very high level of conversation over
> the years on qemu-devel and throwing around nacks just lowers the
> overall tone.

In that case, what's a good way to clarify that one is opposed to the
idea, not the implementation?

We have Acked-by: versus Reviewed-by: on the positive side,
and I was looking for something like this on the negative
side.

> 
> If you can't think of anything better to say than NACK, don't even
> bother sending the email in the first place.

I did add motivation too, it was snipped in the response.

> Regards,
> 
> Anthony Liguori
> 
> >
> > No words have been spent on NAKs yet (... since my subscription, that
> > is). Is this stuff formalized somewhere?
> >
> > Sorry for wasting time...
> >
> > Thanks,
> > Laszlo

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Andreas Färber]

Am 21.08.2013 19:01, schrieb Michael S. Tsirkin:
> On Wed, Aug 21, 2013 at 06:43:16PM +0200, Paolo Bonzini wrote:
>> The pvpanic situation is already messed up enough.  Let us give our
>> libvirt friends an easy indication that we have untied our side.
>>
>> Not-yet-signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ... because we first have to determine how to expose the device's existence
>>     in the ACPI tables or in fw_cfg.
>>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> 
> So it's isa-pvpanic meaning "I-am-sure-this-is-the-last-bug-pvpanic"
> 
> If we feel there's need to give libvirt a way to do
> introspection into QEMU bugs, let's architect one.
> Randomly renaming devices in the vain hope it's
> the last major bug is not it.
> 
> NACK

Seconded. While we shouldn't rule out renaming devices, doing so as a
criteria for libvirt sounds utterly wrong.

Paolo, you are right that a single "NACK" cannot be a criteria, but a
single convincing justification by a random reviewer should be
sufficient to reconsider. :)

Adding some device property or obtaining the info via some existing
query-* QMP command might be better alternatives.

Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

Re: [Qemu-devel] [PATCH 3/3] pvpanic: rename to isa-pvpanic

[Paolo Bonzini]

Il 21/08/2013 19:35, Andreas Färber ha scritto:
> Am 21.08.2013 19:01, schrieb Michael S. Tsirkin:
>> On Wed, Aug 21, 2013 at 06:43:16PM +0200, Paolo Bonzini wrote:
>>> The pvpanic situation is already messed up enough.  Let us give our
>>> libvirt friends an easy indication that we have untied our side.
>>>
>>> Not-yet-signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>>> ... because we first have to determine how to expose the device's existence
>>>     in the ACPI tables or in fw_cfg.
>>>
>>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>>
>> So it's isa-pvpanic meaning "I-am-sure-this-is-the-last-bug-pvpanic"
>>
>> If we feel there's need to give libvirt a way to do
>> introspection into QEMU bugs, let's architect one.
>> Randomly renaming devices in the vain hope it's
>> the last major bug is not it.
>>
>> NACK
> 
> Seconded. While we shouldn't rule out renaming devices, doing so as a
> criteria for libvirt sounds utterly wrong.
> 
> Paolo, you are right that a single "NACK" cannot be a criteria, but a
> single convincing justification by a random reviewer should be
> sufficient to reconsider. :)
> 
> Adding some device property or obtaining the info via some existing
> query-* QMP command might be better alternatives.

Device properties are a good way to communicate changes to the guest,
but here the guest ABI is unchanged.

Anyhow, this patch is not strictly necessary.  It's just a safety net to
avoid that libvirt uses a buggy device on buggy versions of QEMU.

Paolo

Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Daniel P. Berrange]

On Wed, Aug 21, 2013 at 06:43:13PM +0200, Paolo Bonzini wrote:
> The pvpanic mess is even bigger than anticipated.  Let's fix the monitor's
> behavior (patch 1), get rid of all traces that the broken pvpanic existed
> (patch 2), and give it a new name so that libvirt can detect a design
> that works (patch 3).
> 
> All downstreams are urged to apply patches 1+2 as soon as they are
> merged in QEMU.
> 
> Still, there are still other problems to solve.
> 
> In QEMU, exposing "-device isa-pvpanic" in the ACPI tables.  Quite frankly
> I don't have the time to fix this.  We have ~3 months though.  Patch 3
> should not be applied until it is fixed.
> 
> Also, libvirt needs to know under which circumstances to add "-device
> isa-pvpanic", besides obviously the availability of the device.
> 
> IMHO it is just too complicated to retrofit all complications in
> <on_crash>.  In fact, I suspect <on_crash> would match more closely QEMU's
> "internal error" state, and it would be quite useful to add that to the
> QEMU driver.
> 
> Thus, libvirt could add support for an <on_panic> element with the
> following values:

No, <on_crash> is the right thing to be using for this from
libvirt's pov & I don't think we should invent something new.
The <on_crash> element has always been intended to represent
handling of guest panics, not qemu internal errors.

Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|

Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Paolo Bonzini]

Il 21/08/2013 18:48, Daniel P. Berrange ha scritto:
> No, <on_crash> is the right thing to be using for this from
> libvirt's pov & I don't think we should invent something new.
> The <on_crash> element has always been intended to represent
> handling of guest panics, not qemu internal errors.

Actually for Xen HVM guests, it mostly traps things such as failed
vmentries.  The Xen PV-on-HVM drivers do not register a panic notifier
that moves the guest to the "crashed" state.

<on_crash> cannot be salvaged, in my opinion, because all domain XMLs in
the wild will have a setting that causes libvirt to add "-device
isa-pvpanic".  Thus changing libvirt versions will change guest
hardware, which is _very_ bad.

In addition, Windows XP and 2003 will show the annoying device wizard
upon a libvirt upgrade, and fixing this is what surfaced all the mess.

Paolo

Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Daniel P. Berrange]

On Wed, Aug 21, 2013 at 06:51:11PM +0200, Paolo Bonzini wrote:
> Il 21/08/2013 18:48, Daniel P. Berrange ha scritto:
> > No, <on_crash> is the right thing to be using for this from
> > libvirt's pov & I don't think we should invent something new.
> > The <on_crash> element has always been intended to represent
> > handling of guest panics, not qemu internal errors.
> 
> Actually for Xen HVM guests, it mostly traps things such as failed
> vmentries.  The Xen PV-on-HVM drivers do not register a panic notifier
> that moves the guest to the "crashed" state.
> 
> <on_crash> cannot be salvaged, in my opinion, because all domain XMLs in
> the wild will have a setting that causes libvirt to add "-device
> isa-pvpanic".  Thus changing libvirt versions will change guest
> hardware, which is _very_ bad.
> 
> In addition, Windows XP and 2003 will show the annoying device wizard
> upon a libvirt upgrade, and fixing this is what surfaced all the mess.

The existance of a <on_crash> element should not be having any
effect on what hardware we create. That is merely a lifecycle
policy setting that should be completely independant of the
guest device model.

eg it is valid to have <on_crash> present in the XML at all
times, even if there's no pvpanic device present. That simply
means the actions will never be triggered.


Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|

Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Paolo Bonzini]

Il 21/08/2013 18:55, Daniel P. Berrange ha scritto:
> On Wed, Aug 21, 2013 at 06:51:11PM +0200, Paolo Bonzini wrote:
>> Il 21/08/2013 18:48, Daniel P. Berrange ha scritto:
>>> No, <on_crash> is the right thing to be using for this from
>>> libvirt's pov & I don't think we should invent something new.
>>> The <on_crash> element has always been intended to represent
>>> handling of guest panics, not qemu internal errors.
>>
>> Actually for Xen HVM guests, it mostly traps things such as failed
>> vmentries.  The Xen PV-on-HVM drivers do not register a panic notifier
>> that moves the guest to the "crashed" state.
>>
>> <on_crash> cannot be salvaged, in my opinion, because all domain XMLs in
>> the wild will have a setting that causes libvirt to add "-device
>> isa-pvpanic".  Thus changing libvirt versions will change guest
>> hardware, which is _very_ bad.
>>
>> In addition, Windows XP and 2003 will show the annoying device wizard
>> upon a libvirt upgrade, and fixing this is what surfaced all the mess.
> 
> The existance of a <on_crash> element should not be having any
> effect on what hardware we create. That is merely a lifecycle
> policy setting that should be completely independant of the
> guest device model.
> 
> eg it is valid to have <on_crash> present in the XML at all
> times, even if there's no pvpanic device present. That simply
> means the actions will never be triggered.

So are you suggesting to add a <pvpanic/> element to <devices>?  That
may be fine, but it doesn't seem very user-friendly.

Paolo

Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 594 bytes --]

On 08/21/2013 10:56 AM, Paolo Bonzini wrote:
>> eg it is valid to have <on_crash> present in the XML at all
>> times, even if there's no pvpanic device present. That simply
>> means the actions will never be triggered.
> 
> So are you suggesting to add a <pvpanic/> element to <devices>?  That
> may be fine, but it doesn't seem very user-friendly.

No less friendly than having a <memballoon> device, and certainly
automatable via libosinfo integration into virt-install.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Paolo Bonzini]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Il 21/08/2013 19:10, Eric Blake ha scritto:
> On 08/21/2013 10:56 AM, Paolo Bonzini wrote:
>>> eg it is valid to have <on_crash> present in the XML at all 
>>> times, even if there's no pvpanic device present. That simply 
>>> means the actions will never be triggered.
>> 
>> So are you suggesting to add a <pvpanic/> element to <devices>?
>> That may be fine, but it doesn't seem very user-friendly.
> 
> No less friendly than having a <memballoon> device, and certainly 
> automatable via libosinfo integration into virt-install.

Fair enough.  Still I'm not sure that a new <on_panic> element should
be ruled out, see my other message.

Paolo
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Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Daniel P. Berrange]

On Wed, Aug 21, 2013 at 06:56:52PM +0200, Paolo Bonzini wrote:
> Il 21/08/2013 18:55, Daniel P. Berrange ha scritto:
> > On Wed, Aug 21, 2013 at 06:51:11PM +0200, Paolo Bonzini wrote:
> >> Il 21/08/2013 18:48, Daniel P. Berrange ha scritto:
> >>> No, <on_crash> is the right thing to be using for this from
> >>> libvirt's pov & I don't think we should invent something new.
> >>> The <on_crash> element has always been intended to represent
> >>> handling of guest panics, not qemu internal errors.
> >>
> >> Actually for Xen HVM guests, it mostly traps things such as failed
> >> vmentries.  The Xen PV-on-HVM drivers do not register a panic notifier
> >> that moves the guest to the "crashed" state.
> >>
> >> <on_crash> cannot be salvaged, in my opinion, because all domain XMLs in
> >> the wild will have a setting that causes libvirt to add "-device
> >> isa-pvpanic".  Thus changing libvirt versions will change guest
> >> hardware, which is _very_ bad.
> >>
> >> In addition, Windows XP and 2003 will show the annoying device wizard
> >> upon a libvirt upgrade, and fixing this is what surfaced all the mess.
> > 
> > The existance of a <on_crash> element should not be having any
> > effect on what hardware we create. That is merely a lifecycle
> > policy setting that should be completely independant of the
> > guest device model.
> > 
> > eg it is valid to have <on_crash> present in the XML at all
> > times, even if there's no pvpanic device present. That simply
> > means the actions will never be triggered.
> 
> So are you suggesting to add a <pvpanic/> element to <devices>?  That
> may be fine, but it doesn't seem very user-friendly.

Yes, if we're going to have pvpanic be user controllable, it must be
via an explicit device element. 

None of the <on_XXXX> elements should have any impact on guest ABI
model. They're purely lifecycle policy settings.

Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|

Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 2949 bytes --]

On 08/21/2013 10:51 AM, Paolo Bonzini wrote:
> Il 21/08/2013 18:48, Daniel P. Berrange ha scritto:
>> No, <on_crash> is the right thing to be using for this from
>> libvirt's pov & I don't think we should invent something new.
>> The <on_crash> element has always been intended to represent
>> handling of guest panics, not qemu internal errors.
> 
> Actually for Xen HVM guests, it mostly traps things such as failed
> vmentries.  The Xen PV-on-HVM drivers do not register a panic notifier
> that moves the guest to the "crashed" state.
> 
> <on_crash> cannot be salvaged, in my opinion, because all domain XMLs in
> the wild will have a setting that causes libvirt to add "-device
> isa-pvpanic".  Thus changing libvirt versions will change guest
> hardware, which is _very_ bad.

Let's expand on that statement:

Libvirt's default for <on_crash> is 'destroy'.  But virt-install (and
thus virt-manager) have been setting explicit 'restart' for AGES now.

Arguably, this is YET ANOTHER reason why virt-manager should be using
libosinfo to make sane choices about new guest XML, based on known
capabilities of the guest it will be installing.  But that only affects
newly created guests after we fix the virt stack.

In the meantime, you have a point that we have a back-compat mess - we
promise ABI stability (guests shall not see hardware changes when
upgrading versions of libvirtd but leaving the XML unchanged - the only
way to change hardware seen by an existing guest is to explicitly modify
XML).

> 
> In addition, Windows XP and 2003 will show the annoying device wizard
> upon a libvirt upgrade, and fixing this is what surfaced all the mess.

Yes, so we need the back-compat code to leave pvpanic out of
pre-existing guests, if we can find a way to sensibly do that.

So, this boils down to a question of what SHOULD the valid states for
<on_crash> be?  Generically, we want <on_crash>destroy</on_crash> to not
invalidate a guest, but also to not instantiate a pvpanic device; since
that covers the libvirt defaults.  We also want
<on_crash>restart</on_crash> to not invalidate a guest, but also to not
instantiate a pvpanic device, since so many existing guests have that
setting thanks to virt-install.

Maybe that means we add attributes/sub-elements to <on_crash> that
express whether pvpanic device is permitted; and the absence of that
attribute means the status quo (the <on_crash> tag is effectively
ignored because without pvpanic device, there is no way for libvirt to
learn if a guest panicked).  Or does it mean we expose a new sub-element
of <devices>, similar to how we have a <memballoon> subelement that
controls whether the memballoon device is show to the guest, and just
document that for qemu, <on_crash> is a no-op without the <pvpanic>
subelement?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Paolo Bonzini]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Il 21/08/2013 19:02, Eric Blake ha scritto:
> So, this boils down to a question of what SHOULD the valid states
> for <on_crash> be?  Generically, we want
> <on_crash>destroy</on_crash> to not invalidate a guest, but also to
> not instantiate a pvpanic device; since that covers the libvirt
> defaults.  We also want <on_crash>restart</on_crash> to not
> invalidate a guest, but also to not instantiate a pvpanic device,
> since so many existing guests have that setting thanks to
> virt-install.
> 
> Maybe that means we add attributes/sub-elements to <on_crash> that 
> express whether pvpanic device is permitted; and the absence of
> that attribute means the status quo (the <on_crash> tag is
> effectively ignored because without pvpanic device, there is no way
> for libvirt to learn if a guest panicked).  Or does it mean we
> expose a new sub-element of <devices>, similar to how we have a
> <memballoon> subelement that controls whether the memballoon device
> is show to the guest, and just document that for qemu, <on_crash>
> is a no-op without the <pvpanic> subelement?

Perhaps <panic_notifier bus='isa'/> is better?  Note that for s390
<on_crash> works without <pvpanic>.

Anyway yes, that's a possibility.

More precisely, you could still use <on_crash> for internal errors
even without having anything in <devices> (Xen conflates panics and
internal errors).

But then, "pause" and "ignore" are useful on-panic policies, yet they
do not make sense for internal errors.  Hence my suggestion to
introduce a new element <on_panic>.  We can still make <on_panic> a
no-op without the appropriate element under <devices>.

Paolo
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Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Michael S. Tsirkin]

On Wed, Aug 21, 2013 at 11:02:56AM -0600, Eric Blake wrote:
> On 08/21/2013 10:51 AM, Paolo Bonzini wrote:
> > Il 21/08/2013 18:48, Daniel P. Berrange ha scritto:
> >> No, <on_crash> is the right thing to be using for this from
> >> libvirt's pov & I don't think we should invent something new.
> >> The <on_crash> element has always been intended to represent
> >> handling of guest panics, not qemu internal errors.
> > 
> > Actually for Xen HVM guests, it mostly traps things such as failed
> > vmentries.  The Xen PV-on-HVM drivers do not register a panic notifier
> > that moves the guest to the "crashed" state.
> > 
> > <on_crash> cannot be salvaged, in my opinion, because all domain XMLs in
> > the wild will have a setting that causes libvirt to add "-device
> > isa-pvpanic".  Thus changing libvirt versions will change guest
> > hardware, which is _very_ bad.
> 
> Let's expand on that statement:
> 
> Libvirt's default for <on_crash> is 'destroy'.  But virt-install (and
> thus virt-manager) have been setting explicit 'restart' for AGES now.
> 
> Arguably, this is YET ANOTHER reason why virt-manager should be using
> libosinfo to make sane choices about new guest XML, based on known
> capabilities of the guest it will be installing.  But that only affects
> newly created guests after we fix the virt stack.
> 
> In the meantime, you have a point that we have a back-compat mess - we
> promise ABI stability (guests shall not see hardware changes when
> upgrading versions of libvirtd but leaving the XML unchanged - the only
> way to change hardware seen by an existing guest is to explicitly modify
> XML).
> 
> > 
> > In addition, Windows XP and 2003 will show the annoying device wizard
> > upon a libvirt upgrade, and fixing this is what surfaced all the mess.
> 
> Yes, so we need the back-compat code to leave pvpanic out of
> pre-existing guests, if we can find a way to sensibly do that.
> 
> So, this boils down to a question of what SHOULD the valid states for
> <on_crash> be?  Generically, we want <on_crash>destroy</on_crash> to not
> invalidate a guest, but also to not instantiate a pvpanic device; since
> that covers the libvirt defaults.  We also want
> <on_crash>restart</on_crash> to not invalidate a guest, but also to not
> instantiate a pvpanic device, since so many existing guests have that
> setting thanks to virt-install.
> 
> Maybe that means we add attributes/sub-elements to <on_crash> that
> express whether pvpanic device is permitted; and the absence of that
> attribute means the status quo (the <on_crash> tag is effectively
> ignored because without pvpanic device, there is no way for libvirt to
> learn if a guest panicked).  Or does it mean we expose a new sub-element
> of <devices>, similar to how we have a <memballoon> subelement that
> controls whether the memballoon device is show to the guest, and just
> document that for qemu, <on_crash> is a no-op without the <pvpanic>
> subelement?


This is a QEMU bug that you happened to be Cc'd on.
So you started worry about supporting a buggy QEMU.
This is generally futile.

There are uncounted bugs that we silently fixed.
They are often much more major than this silly reversibility bug.
Some bios versions have racy hotplug support so
hotplug event can be missed.
Should libvirt warn the user that bios is broken
and suggest restarting guest to see the device?
Some QEMU versions had a racy implementation of virtio
that would corrupt guest memory.
Should libvirt warn the user that virtio is broken
and suggest switching to e1000 or upgrading QEMU?
Some QEMU versions have buggy qcow2 that would corrupt disk.
Should libvirt warn the user that qcow2 is broken
and suggest switching to raw?
Some kernels have buggy vhost drivers which would crash host.
Should libvirt detect these and tell user to upgrade kernel
or switch to userspace virtio?
Some kernels have NIC drivers that brick hardware.
Should libvirt detect these and tell user to upgrade kernel
or switch to a different NIC?
There are libc bugs, glib bugs ....

Let's fix the bug in QEMU and move on.
Working around them in libvirt is unnecessary.


-- 
MST

Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Paolo Bonzini]

Il 21/08/2013 19:26, Michael S. Tsirkin ha scritto:
> This is a QEMU bug that you happened to be Cc'd on.

Michael, this is bullshit and you know.  I know you're more intelligent
than this.  Stop it, please.

Paolo