RE: [RFC v4 7/8] hisi_acc_vfio_pci: Add support for VFIO live migration

[Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>]

> -----Original Message-----
> From: Jason Gunthorpe [mailto:jgg@nvidia.com]
> Sent: 08 February 2022 15:22
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> Cc: kvm@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-crypto@vger.kernel.org; alex.williamson@redhat.com;
> cohuck@redhat.com; mgurtovoy@nvidia.com; yishaih@nvidia.com; Linuxarm
> <linuxarm@huawei.com>; liulongfang <liulongfang@huawei.com>; Zengtao (B)
> <prime.zeng@hisilicon.com>; Jonathan Cameron
> <jonathan.cameron@huawei.com>; Wangzhou (B) <wangzhou1@hisilicon.com>
> Subject: Re: [RFC v4 7/8] hisi_acc_vfio_pci: Add support for VFIO live
> migration
> 
> On Tue, Feb 08, 2022 at 01:34:24PM +0000, Shameer Kolothum wrote:
> 
> Overall this looks like a fine implementation, as far as I can tell it
> meets the uAPI design perfectly.
> 
> Why did you decide not to do the P2P support?

I need to check that with our hardware folks. May be it is in pipeline. 

> > +static struct file *
> > +hisi_acc_vf_set_device_state(struct hisi_acc_vf_core_device *hisi_acc_vdev,
> > +			     u32 new)
> > +{
> > +	u32 cur = hisi_acc_vdev->mig_state;
> > +	int ret;
> > +
> > +	if (cur == VFIO_DEVICE_STATE_RUNNING && new ==
> VFIO_DEVICE_STATE_STOP) {
> > +		ret = hisi_acc_vf_stop_device(hisi_acc_vdev);
> > +		if (ret)
> > +			return ERR_PTR(ret);
> 
> Be mindful that qemu doesn't handle a failure here very well, I'm not
> sure we will be able to fix this in the short term.

Ok. I will check that and see how big of a problem it is.

> > +static int hisi_acc_vfio_pci_init(struct hisi_acc_vf_core_device
> *hisi_acc_vdev)
> > +{
> > +	struct vfio_pci_core_device *vdev = &hisi_acc_vdev->core_device;
> > +	struct pci_dev *vf_dev = vdev->pdev;
> > +	struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm;
> > +
> > +	/*
> > +	 * ACC VF dev BAR2 region consists of both functional register space
> > +	 * and migration control register space. For migration to work, we
> > +	 * need access to both. Hence, we map the entire BAR2 region here.
> > +	 * But from a security point of view, we restrict access to the
> > +	 * migration control space from Guest(Please see mmap/ioctl/read/write
> > +	 * override functions).
> > +	 *
> > +	 * Also the HiSilicon ACC VF devices supported by this driver on
> > +	 * HiSilicon hardware platforms are integrated end point devices
> > +	 * and has no capability to perform PCIe P2P.
> > +	 */
> > +	vf_qm->io_base =
> > +		ioremap(pci_resource_start(vf_dev, VFIO_PCI_BAR2_REGION_INDEX),
> > +			pci_resource_len(vf_dev, VFIO_PCI_BAR2_REGION_INDEX));
> > +	if (!vf_qm->io_base)
> > +		return -EIO;
> > +
> > +	vf_qm->fun_type = QM_HW_VF;
> > +	vf_qm->pdev = vf_dev;
> > +	mutex_init(&vf_qm->mailbox_lock);
> 
> mailbox_lock seems unused

I think we need that as that will be used in the QM driver APIs. I will add a
comment here.

> > +	hisi_acc_vdev->vf_id = PCI_FUNC(vf_dev->devfn);
> 
> Does this need to use the pci_iov_vf_id() function? funcs don't need
> to be tightly packed, necessarily.
> 
> This should be set when the structure is allocated, not at open time.

Ok. I will change and move it.
 
> > +	hisi_acc_vdev->vf_dev = vf_dev;
> > +	vf_qm->dev_name = hisi_acc_vdev->pf_qm->dev_name;
> 
> Also unused

I will see if we can get rid of it if it is not used by QM driver APIs used here.

> 
> > +	hisi_acc_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;
> > +
> > +	return 0;
> > +}
> >
> >  static int hisi_acc_pci_rw_access_check(struct vfio_device *core_vdev,
> >  					size_t count, loff_t *ppos,
> > @@ -129,63 +1067,96 @@ static long hisi_acc_vfio_pci_ioctl(struct
> vfio_device *core_vdev, unsigned int
> >
> >  static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev)
> >  {
> > -	struct vfio_pci_core_device *vdev =
> > -		container_of(core_vdev, struct vfio_pci_core_device, vdev);
> > +	struct hisi_acc_vf_core_device *hisi_acc_vdev = container_of(core_vdev,
> > +			struct hisi_acc_vf_core_device, core_device.vdev);
> > +	struct vfio_pci_core_device *vdev = &hisi_acc_vdev->core_device;
> >  	int ret;
> >
> >  	ret = vfio_pci_core_enable(vdev);
> >  	if (ret)
> >  		return ret;
> >
> > -	vfio_pci_core_finish_enable(vdev);
> > +	if (!hisi_acc_vdev->migration_support) {
> 
> This should just test the core flag and get rid of migration_support:

Ok.

> 
> 		hisi_acc_vdev->core_device.vdev.migration_flags =
> 			VFIO_MIGRATION_STOP_COPY;
> 
> > +++ b/drivers/vfio/pci/hisi_acc_vfio_pci.h
> > @@ -0,0 +1,119 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/* Copyright (c) 2021 HiSilicon Ltd. */
> > +
> > +#ifndef HISI_ACC_VFIO_PCI_H
> > +#define HISI_ACC_VFIO_PCI_H
> > +
> > +#include <linux/hisi_acc_qm.h>
> > +
> > +#define VDM_OFFSET(x) offsetof(struct vfio_device_migration_info, x)
> > +
> > +#define HISI_ACC_MIG_REGION_DATA_OFFSET                \
> > +	(sizeof(struct vfio_device_migration_info))
> > +
> > +#define HISI_ACC_MIG_REGION_DATA_SIZE (sizeof(struct acc_vf_data))
> 
> These three are not used any more

True.

> 
> > +struct acc_vf_data {
> > +#define QM_MATCH_SIZE 32L
> > +	/* QM match information */
> > +	u32 qp_num;
> > +	u32 dev_id;
> > +	u32 que_iso_cfg;
> > +	u32 qp_base;
> > +	/* QM reserved 4 match information */
> > +	u32 qm_rsv_state[4];
> > +
> > +	/* QM RW regs */
> > +	u32 aeq_int_mask;
> > +	u32 eq_int_mask;
> > +	u32 ifc_int_source;
> > +	u32 ifc_int_mask;
> > +	u32 ifc_int_set;
> > +	u32 page_size;
> > +
> > +	/* QM_EQC_DW has 7 regs */
> > +	u32 qm_eqc_dw[7];
> > +
> > +	/* QM_AEQC_DW has 7 regs */
> > +	u32 qm_aeqc_dw[7];
> > +
> > +	/* QM reserved 5 regs */
> > +	u32 qm_rsv_regs[5];
> > +
> > +	/* qm memory init information */
> > +	dma_addr_t eqe_dma;
> > +	dma_addr_t aeqe_dma;
> > +	dma_addr_t sqc_dma;
> > +	dma_addr_t cqc_dma;
> 
> You can't put dma_addr_t in a structure that needs to go
> on-the-wire. This should be u64

Ok.

Thanks,
Shameer
 
> > +};
> > +
> > +struct hisi_acc_vf_migration_file {
> > +	struct file *filp;
> > +	struct mutex lock;
> > +	bool disabled;
> > +
> > +	struct acc_vf_data vf_data;
> > +	size_t total_length;
> > +};
> > +
> > +struct hisi_acc_vf_core_device {
> > +	struct vfio_pci_core_device core_device;
> > +	u8 migration_support:1;
> > +	/* for migration state */
> > +	struct mutex state_mutex;
> > +	enum vfio_device_mig_state mig_state;
> > +	struct pci_dev *pf_dev;
> > +	struct pci_dev *vf_dev;
> > +	struct hisi_qm *pf_qm;
> > +	struct hisi_qm vf_qm;
> > +	int vf_id;
> > +
> > +	struct hisi_acc_vf_migration_file *resuming_migf;
> > +	struct hisi_acc_vf_migration_file *saving_migf;
> > +};
> > +#endif /* HISI_ACC_VFIO_PCI_H */