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Re: [Qemu-ppc] [PATCH v2] virtio-pci: fix migration for pci bus master
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From: |
Greg Kurz |
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Subject: |
Re: [Qemu-ppc] [PATCH v2] virtio-pci: fix migration for pci bus master |
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Date: |
Wed, 15 Oct 2014 17:34:25 +0200 |
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 ?
> + 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(),
> };