Re: [PATCH v16 QEMU 04/16] vfio: Add save and load functions for VFIO PCI devices

[Kirti Wankhede <kwankhede@nvidia.com>]

On 4/7/2020 9:40 AM, Longpeng (Mike, Cloud Infrastructure Service 
Product Dept.) wrote:
> 
> 
> On 2020/3/25 5:09, Kirti Wankhede wrote:
>> These functions save and restore PCI device specific data - config
>> space of PCI device.
>> Tested save and restore with MSI and MSIX type.
>>
>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>> ---
>>   hw/vfio/pci.c                 | 163 ++++++++++++++++++++++++++++++++++++++++++
>>   include/hw/vfio/vfio-common.h |   2 +
>>   2 files changed, 165 insertions(+)
>>
>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>> index 6c77c12e44b9..8deb11e87ef7 100644
>> --- a/hw/vfio/pci.c
>> +++ b/hw/vfio/pci.c
>> @@ -41,6 +41,7 @@
>>   #include "trace.h"
>>   #include "qapi/error.h"
>>   #include "migration/blocker.h"
>> +#include "migration/qemu-file.h"
>>   
>>   #define TYPE_VFIO_PCI "vfio-pci"
>>   #define PCI_VFIO(obj)    OBJECT_CHECK(VFIOPCIDevice, obj, TYPE_VFIO_PCI)
>> @@ -1632,6 +1633,50 @@ static void vfio_bars_prepare(VFIOPCIDevice *vdev)
>>       }
>>   }
>>   
>> +static int vfio_bar_validate(VFIOPCIDevice *vdev, int nr)
>> +{
>> +    PCIDevice *pdev = &vdev->pdev;
>> +    VFIOBAR *bar = &vdev->bars[nr];
>> +    uint64_t addr;
>> +    uint32_t addr_lo, addr_hi = 0;
>> +
>> +    /* Skip unimplemented BARs and the upper half of 64bit BARS. */
>> +    if (!bar->size) {
>> +        return 0;
>> +    }
>> +
>> +    addr_lo = pci_default_read_config(pdev, PCI_BASE_ADDRESS_0 + nr * 4, 4);
>> +
>> +    addr_lo = addr_lo & (bar->ioport ? PCI_BASE_ADDRESS_IO_MASK :
>> +                                       PCI_BASE_ADDRESS_MEM_MASK);
>> +    if (bar->type == PCI_BASE_ADDRESS_MEM_TYPE_64) {
>> +        addr_hi = pci_default_read_config(pdev,
>> +                                         PCI_BASE_ADDRESS_0 + (nr + 1) * 4, 4);
>> +    }
>> +
>> +    addr = ((uint64_t)addr_hi << 32) | addr_lo;
>> +
>> +    if (!QEMU_IS_ALIGNED(addr, bar->size)) {
>> +        return -EINVAL;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static int vfio_bars_validate(VFIOPCIDevice *vdev)
>> +{
>> +    int i, ret;
>> +
>> +    for (i = 0; i < PCI_ROM_SLOT; i++) {
>> +        ret = vfio_bar_validate(vdev, i);
>> +        if (ret) {
>> +            error_report("vfio: BAR address %d validation failed", i);
>> +            return ret;
>> +        }
>> +    }
>> +    return 0;
>> +}
>> +
>>   static void vfio_bar_register(VFIOPCIDevice *vdev, int nr)
>>   {
>>       VFIOBAR *bar = &vdev->bars[nr];
>> @@ -2414,11 +2459,129 @@ static Object *vfio_pci_get_object(VFIODevice *vbasedev)
>>       return OBJECT(vdev);
>>   }
>>   
>> +static void vfio_pci_save_config(VFIODevice *vbasedev, QEMUFile *f)
>> +{
>> +    VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
>> +    PCIDevice *pdev = &vdev->pdev;
>> +    uint16_t pci_cmd;
>> +    int i;
>> +
>> +    for (i = 0; i < PCI_ROM_SLOT; i++) {
>> +        uint32_t bar;
>> +
>> +        bar = pci_default_read_config(pdev, PCI_BASE_ADDRESS_0 + i * 4, 4);
>> +        qemu_put_be32(f, bar);
>> +    }
>> +
>> +    qemu_put_be32(f, vdev->interrupt);
>> +    if (vdev->interrupt == VFIO_INT_MSI) {
>> +        uint32_t msi_flags, msi_addr_lo, msi_addr_hi = 0, msi_data;
>> +        bool msi_64bit;
>> +
>> +        msi_flags = pci_default_read_config(pdev, pdev->msi_cap + PCI_MSI_FLAGS,
>> +                                            2);
>> +        msi_64bit = (msi_flags & PCI_MSI_FLAGS_64BIT);
>> +
>> +        msi_addr_lo = pci_default_read_config(pdev,
>> +                                         pdev->msi_cap + PCI_MSI_ADDRESS_LO, 4);
>> +        qemu_put_be32(f, msi_addr_lo);
>> +
>> +        if (msi_64bit) {
>> +            msi_addr_hi = pci_default_read_config(pdev,
>> +                                             pdev->msi_cap + PCI_MSI_ADDRESS_HI,
>> +                                             4);
>> +        }
>> +        qemu_put_be32(f, msi_addr_hi);
>> +
>> +        msi_data = pci_default_read_config(pdev,
>> +                pdev->msi_cap + (msi_64bit ? PCI_MSI_DATA_64 : PCI_MSI_DATA_32),
>> +                2);
>> +        qemu_put_be32(f, msi_data);
>> +    } else if (vdev->interrupt == VFIO_INT_MSIX) {
>> +        uint16_t offset;
>> +
>> +        /* save enable bit and maskall bit */
>> +        offset = pci_default_read_config(pdev,
>> +                                       pdev->msix_cap + PCI_MSIX_FLAGS + 1, 2);
>> +        qemu_put_be16(f, offset);
>> +        msix_save(pdev, f);
>> +    }
>> +    pci_cmd = pci_default_read_config(pdev, PCI_COMMAND, 2);
>> +    qemu_put_be16(f, pci_cmd);
>> +}
>> +
>> +static int vfio_pci_load_config(VFIODevice *vbasedev, QEMUFile *f)
>> +{
>> +    VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
>> +    PCIDevice *pdev = &vdev->pdev;
>> +    uint32_t interrupt_type;
>> +    uint32_t msi_flags, msi_addr_lo, msi_addr_hi = 0, msi_data;
>> +    uint16_t pci_cmd;
>> +    bool msi_64bit;
>> +    int i, ret;
>> +
>> +    /* retore pci bar configuration */
>> +    pci_cmd = pci_default_read_config(pdev, PCI_COMMAND, 2);
>> +    vfio_pci_write_config(pdev, PCI_COMMAND,
>> +                        pci_cmd & (!(PCI_COMMAND_IO | PCI_COMMAND_MEMORY)), 2);
>> +    for (i = 0; i < PCI_ROM_SLOT; i++) {
>> +        uint32_t bar = qemu_get_be32(f);
>> +
>> +        vfio_pci_write_config(pdev, PCI_BASE_ADDRESS_0 + i * 4, bar, 4);
>> +    }
>> +
>> +    ret = vfio_bars_validate(vdev);
>> +    if (ret) {
>> +        return ret;
>> +    }
>> +
>> +    interrupt_type = qemu_get_be32(f);
>> +
>> +    if (interrupt_type == VFIO_INT_MSI) {
>> +        /* restore msi configuration */
>> +        msi_flags = pci_default_read_config(pdev,
>> +                                            pdev->msi_cap + PCI_MSI_FLAGS, 2);
>> +        msi_64bit = (msi_flags & PCI_MSI_FLAGS_64BIT);
>> +
>> +        vfio_pci_write_config(pdev, pdev->msi_cap + PCI_MSI_FLAGS,
>> +                              msi_flags & (!PCI_MSI_FLAGS_ENABLE), 2);
>> +
>> +        msi_addr_lo = qemu_get_be32(f);
>> +        vfio_pci_write_config(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_LO,
>> +                              msi_addr_lo, 4);
>> +
>> +        msi_addr_hi = qemu_get_be32(f);
>> +        if (msi_64bit) {
>> +            vfio_pci_write_config(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI,
>> +                                  msi_addr_hi, 4);
>> +        }
>> +        msi_data = qemu_get_be32(f);
>> +        vfio_pci_write_config(pdev,
>> +                pdev->msi_cap + (msi_64bit ? PCI_MSI_DATA_64 : PCI_MSI_DATA_32),
>> +                msi_data, 2);
>> +
>> +        vfio_pci_write_config(pdev, pdev->msi_cap + PCI_MSI_FLAGS,
>> +                              msi_flags | PCI_MSI_FLAGS_ENABLE, 2);
>> +    } else if (interrupt_type == VFIO_INT_MSIX) {
>> +        uint16_t offset = qemu_get_be16(f);
>> +
>> +        /* load enable bit and maskall bit */
>> +        vfio_pci_write_config(pdev, pdev->msix_cap + PCI_MSIX_FLAGS + 1,
>> +                              offset, 2);
>> +        msix_load(pdev, f);
> Hi Kirti, Alex
> 
> 'msix_load' here may increases the downtime. Our migrate-cap device has 128 msix
> interrupts and the guestos enables all of them, so cost a lot of time (nearly
> 1s) to do 'msix_load', because in 'vfio_msix_vector_do_use' we need disable all
> old interuppts and then append a new one.
> 
> What's your opinions ?
> 

This will be at destination, so device should not be running which means 
interrupts should be disabled already, right?
You only need to append new.

Thanks,
Kirti

>> +    }
>> +    pci_cmd = qemu_get_be16(f);
>> +    vfio_pci_write_config(pdev, PCI_COMMAND, pci_cmd, 2);
>> +    return 0;
>> +}
>> +
>>   static VFIODeviceOps vfio_pci_ops = {
>>       .vfio_compute_needs_reset = vfio_pci_compute_needs_reset,
>>       .vfio_hot_reset_multi = vfio_pci_hot_reset_multi,
>>       .vfio_eoi = vfio_intx_eoi,
>>       .vfio_get_object = vfio_pci_get_object,
>> +    .vfio_save_config = vfio_pci_save_config,
>> +    .vfio_load_config = vfio_pci_load_config,
>>   };
>>   
>>   int vfio_populate_vga(VFIOPCIDevice *vdev, Error **errp)
>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
>> index 74261feaeac9..d69a7f3ae31e 100644
>> --- a/include/hw/vfio/vfio-common.h
>> +++ b/include/hw/vfio/vfio-common.h
>> @@ -120,6 +120,8 @@ struct VFIODeviceOps {
>>       int (*vfio_hot_reset_multi)(VFIODevice *vdev);
>>       void (*vfio_eoi)(VFIODevice *vdev);
>>       Object *(*vfio_get_object)(VFIODevice *vdev);
>> +    void (*vfio_save_config)(VFIODevice *vdev, QEMUFile *f);
>> +    int (*vfio_load_config)(VFIODevice *vdev, QEMUFile *f);
>>   };
>>   
>>   typedef struct VFIOGroup {
>>
>