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Re: [Qemu-devel] [PATCH v2] virtio-pci: fix migration for pci bus master
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From: |
Michael S. Tsirkin |
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Subject: |
Re: [Qemu-devel] [PATCH v2] virtio-pci: fix migration for pci bus master |
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Date: |
Fri, 17 Oct 2014 17:01:31 +0300 |
On Wed, Oct 15, 2014 at 05:34:25PM +0200, Greg Kurz wrote:
> On Tue, 14 Oct 2014 19:55:23 +0300
> "Michael S. Tsirkin" <address@hidden> wrote:
> > Current support for bus master (clearing OK bit) together with the need to
> > support guests which do not enable PCI bus mastering, leads to extra state
> > in
> > VIRTIO_PCI_FLAG_BUS_MASTER_BUG bit, which isn't robust in case of
> > cross-version
> > migration for the case when guests use the device before setting DRIVER_OK.
> >
> > Rip out this code, and replace it:
> > - Modern QEMU doesn't need VIRTIO_PCI_FLAG_BUS_MASTER_BUG
> > so just drop it for latest machine type.
> > - For compat machine types, set PCI_COMMAND if DRIVER_OK
> > is set.
> >
> > As this is needed for 2.1 for both pc and ppc, move PC_COMPAT macros from
> > pc.h
> > to a new common header.
> >
> > Cc: Greg Kurz <address@hidden>
> > Signed-off-by: Michael S. Tsirkin <address@hidden>
> > ---
>
> Just a question, see below.
>
> Apart from that, it looks good.
>
> Reviewed-by: Greg Kurz <address@hidden>
> Tested-by: Greg Kurz <address@hidden>
>
> > hw/virtio/virtio-pci.h | 5 +++++
> > include/hw/compat.h | 16 ++++++++++++++++
> > include/hw/i386/pc.h | 10 ++--------
> > hw/i386/pc_piix.c | 2 +-
> > hw/i386/pc_q35.c | 2 +-
> > hw/ppc/spapr.c | 9 ++++++++-
> > hw/virtio/virtio-pci.c | 29 +++++++++++------------------
> > 7 files changed, 44 insertions(+), 29 deletions(-)
> > create mode 100644 include/hw/compat.h
> >
> > diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
> > index 1cea157..8873b6d 100644
> > --- a/hw/virtio/virtio-pci.h
> > +++ b/hw/virtio/virtio-pci.h
> > @@ -53,6 +53,11 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
> > #define VIRTIO_PCI_BUS_CLASS(klass) \
> > OBJECT_CLASS_CHECK(VirtioPCIBusClass, klass, TYPE_VIRTIO_PCI_BUS)
> >
> > +/* Need to activate work-arounds for buggy guests at vmstate load. */
> > +#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT 0
> > +#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION \
> > + (1 << VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT)
> > +
> > /* Performance improves when virtqueue kick processing is decoupled from
> > the
> > * vcpu thread using ioeventfd for some devices. */
> > #define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
> > diff --git a/include/hw/compat.h b/include/hw/compat.h
> > new file mode 100644
> > index 0000000..47f6ff5
> > --- /dev/null
> > +++ b/include/hw/compat.h
> > @@ -0,0 +1,16 @@
> > +#ifndef HW_COMPAT_H
> > +#define HW_COMPAT_H
> > +
> > +#define HW_COMPAT_2_1 \
> > + {\
> > + .driver = "intel-hda",\
> > + .property = "old_msi_addr",\
> > + .value = "on",\
> > + },\
> > + {\
> > + .driver = "virtio-pci",\
> > + .property = "virtio-pci-bus-master-bug-migration",\
> > + .value = "on",\
> > + }
> > +
> > +#endif /* HW_COMPAT_H */
> > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> > index bae023a..82ad046 100644
> > --- a/include/hw/i386/pc.h
> > +++ b/include/hw/i386/pc.h
> > @@ -14,6 +14,7 @@
> > #include "sysemu/sysemu.h"
> > #include "hw/pci/pci.h"
> > #include "hw/boards.h"
> > +#include "hw/compat.h"
> >
> > #define HPET_INTCAP "hpet-intcap"
> >
> > @@ -307,15 +308,8 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
> > int e820_get_num_entries(void);
> > bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
> >
> > -#define PC_COMPAT_2_1 \
> > - {\
> > - .driver = "intel-hda",\
> > - .property = "old_msi_addr",\
> > - .value = "on",\
> > - }
> > -
> > #define PC_COMPAT_2_0 \
> > - PC_COMPAT_2_1, \
> > + HW_COMPAT_2_1, \
> > {\
> > .driver = "virtio-scsi-pci",\
> > .property = "any_layout",\
> > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > index 553afdd..a1634ab 100644
> > --- a/hw/i386/pc_piix.c
> > +++ b/hw/i386/pc_piix.c
> > @@ -502,7 +502,7 @@ static QEMUMachine pc_i440fx_machine_v2_1 = {
> > .name = "pc-i440fx-2.1",
> > .init = pc_init_pci,
> > .compat_props = (GlobalProperty[]) {
> > - PC_COMPAT_2_1,
> > + HW_COMPAT_2_1,
> > { /* end of list */ }
> > },
> > };
> > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> > index a199043..f330f7a 100644
> > --- a/hw/i386/pc_q35.c
> > +++ b/hw/i386/pc_q35.c
> > @@ -365,7 +365,7 @@ static QEMUMachine pc_q35_machine_v2_1 = {
> > .name = "pc-q35-2.1",
> > .init = pc_q35_init,
> > .compat_props = (GlobalProperty[]) {
> > - PC_COMPAT_2_1,
> > + HW_COMPAT_2_1,
> > { /* end of list */ }
> > },
> > };
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 2becc9f..8bc597f 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -57,6 +57,8 @@
> > #include "trace.h"
> > #include "hw/nmi.h"
> >
> > +#include "hw/compat.h"
> > +
> > #include <libfdt.h>
> >
> > /* SLOF memory layout:
> > @@ -1689,10 +1691,15 @@ static const TypeInfo spapr_machine_info = {
> > static void spapr_machine_2_1_class_init(ObjectClass *oc, void *data)
> > {
> > MachineClass *mc = MACHINE_CLASS(oc);
> > + static GlobalProperty compat_props[] = {
> > + HW_COMPAT_2_1,
> > + { /* end of list */ }
> > + };
> >
> > mc->name = "pseries-2.1";
> > mc->desc = "pSeries Logical Partition (PAPR compliant) v2.1";
> > - mc->is_default = 0;
> > + mc->is_default = -1;
>
> I could find no other place where we set is_default to -1. What's the point ?
Leftover from unrelated code changes.
I'll drop this, good catch!
> > + mc->compat_props = compat_props;
> > }
> >
> > static const TypeInfo spapr_machine_2_1_info = {
> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > index a827cd4..a499a3c 100644
> > --- a/hw/virtio/virtio-pci.c
> > +++ b/hw/virtio/virtio-pci.c
> > @@ -86,9 +86,6 @@
> > * 12 is historical, and due to x86 page size. */
> > #define VIRTIO_PCI_QUEUE_ADDR_SHIFT 12
> >
> > -/* Flags track per-device state like workarounds for quirks in older
> > guests. */
> > -#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG (1 << 0)
> > -
> > static void virtio_pci_bus_new(VirtioBusState *bus, size_t bus_size,
> > VirtIOPCIProxy *dev);
> >
> > @@ -323,14 +320,6 @@ static void virtio_ioport_write(void *opaque, uint32_t
> > addr, uint32_t val)
> > proxy->pci_dev.config[PCI_COMMAND] |
> > PCI_COMMAND_MASTER, 1);
> > }
> > -
> > - /* Linux before 2.6.34 sets the device as OK without enabling
> > - the PCI device bus master bit. In this case we need to disable
> > - some safety checks. */
> > - if ((val & VIRTIO_CONFIG_S_DRIVER_OK) &&
> > - !(proxy->pci_dev.config[PCI_COMMAND] & PCI_COMMAND_MASTER)) {
> > - proxy->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG;
> > - }
> > break;
> > case VIRTIO_MSI_CONFIG_VECTOR:
> > msix_vector_unuse(&proxy->pci_dev, vdev->config_vector);
> > @@ -483,8 +472,7 @@ static void virtio_write_config(PCIDevice *pci_dev,
> > uint32_t address,
> > pci_default_write_config(pci_dev, address, val, len);
> >
> > if (range_covers_byte(address, len, PCI_COMMAND) &&
> > - !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER) &&
> > - !(proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG)) {
> > + !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER)) {
> > virtio_pci_stop_ioeventfd(proxy);
> > virtio_set_status(vdev, vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK);
> > }
> > @@ -895,11 +883,15 @@ static void virtio_pci_vmstate_change(DeviceState *d,
> > bool running)
> > VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> >
> > if (running) {
> > - /* Try to find out if the guest has bus master disabled, but is
> > - in ready state. Then we have a buggy guest OS. */
> > - if ((vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) &&
> > + /* Old QEMU versions did not set bus master enable on status write.
> > + * Detect DRIVER set and enable it.
> > + */
> > + if ((proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION) &&
> > + (vdev->status & VIRTIO_CONFIG_S_DRIVER) &&
> > !(proxy->pci_dev.config[PCI_COMMAND] & PCI_COMMAND_MASTER)) {
> > - proxy->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG;
> > + pci_default_write_config(&proxy->pci_dev, PCI_COMMAND,
> > + proxy->pci_dev.config[PCI_COMMAND] |
> > + PCI_COMMAND_MASTER, 1);
> > }
> > virtio_pci_start_ioeventfd(proxy);
> > } else {
> > @@ -1040,10 +1032,11 @@ static void virtio_pci_reset(DeviceState *qdev)
> > virtio_pci_stop_ioeventfd(proxy);
> > virtio_bus_reset(bus);
> > msix_unuse_all_vectors(&proxy->pci_dev);
> > - proxy->flags &= ~VIRTIO_PCI_FLAG_BUS_MASTER_BUG;
> > }
> >
> > static Property virtio_pci_properties[] = {
> > + DEFINE_PROP_BIT("virtio-pci-bus-master-bug-migration", VirtIOPCIProxy,
> > flags,
> > + VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT, false),
> > DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
> > DEFINE_PROP_END_OF_LIST(),
> > };