On Mon, 16 Dec 2019 11:57:54 +0000 "Liu, Yi L" <yi.l.liu@xxxxxxxxx> wrote: > > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > > Sent: Monday, December 16, 2019 6:47 AM > > To: Liu, Yi L <yi.l.liu@xxxxxxxxx> > > Subject: Re: [PATCH v3 08/10] vfio/pci: protect cap/ecap_perm bits alloc/free > > > > On Thu, 21 Nov 2019 19:23:45 +0800 > > Liu Yi L <yi.l.liu@xxxxxxxxx> wrote: > > > > > This patch add a user numer track for the shared cap/ecap_perms bits, > > > and the alloc/free will hold a semaphore to protect the operations. > > > With the changes, first caller of vfio_pci_init_perm_bits() will > > > initialize the bits. While the last caller of vfio_pci_uninit_perm_bits() > > > will free the bits. This is a preparation to have multiple cap/ecap_perms > > > bits users. > > > > > > Cc: Kevin Tian <kevin.tian@xxxxxxxxx> > > > Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > > > Suggested-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > > > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> > > > --- > > > drivers/vfio/pci/vfio_pci_config.c | 33 +++++++++++++++++++++++++++++++-- > > > 1 file changed, 31 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c > > > index f0891bd..274c993 100644 > > > --- a/drivers/vfio/pci/vfio_pci_config.c > > > +++ b/drivers/vfio/pci/vfio_pci_config.c > > > @@ -36,6 +36,13 @@ > > > (offset >= PCI_ROM_ADDRESS && offset < PCI_ROM_ADDRESS + 4)) > > > > > > /* > > > + * vfio_perm_bits_sem: prorects the shared perm_bits alloc/free > > > + * vfio_pci_perm_bits_users: tracks the user of the shared perm_bits > > > + */ > > > +static DEFINE_SEMAPHORE(vfio_perm_bits_sem); > > > +static int vfio_pci_perm_bits_users; > > > + > > > +/* > > > * Lengths of PCI Config Capabilities > > > * 0: Removed from the user visible capability list > > > * FF: Variable length > > > @@ -995,7 +1002,7 @@ static int __init init_pci_ext_cap_pwr_perm(struct > > perm_bits *perm) > > > /* > > > * Initialize the shared permission tables > > > */ > > > -void vfio_pci_uninit_perm_bits(void) > > > +static void vfio_pci_uninit_perm_bits_internal(void) > > > { > > > free_perm_bits(&cap_perms[PCI_CAP_ID_BASIC]); > > > > > > @@ -1009,10 +1016,30 @@ void vfio_pci_uninit_perm_bits(void) > > > free_perm_bits(&ecap_perms[PCI_EXT_CAP_ID_PWR]); > > > } > > > > > > +void vfio_pci_uninit_perm_bits(void) > > > +{ > > > + down(&vfio_perm_bits_sem); > > > + > > > + if (--vfio_pci_perm_bits_users > 0) > > > + goto out; > > > + > > > + vfio_pci_uninit_perm_bits_internal(); > > > + > > > +out: > > > + up(&vfio_perm_bits_sem); > > > +} > > > + > > > int __init vfio_pci_init_perm_bits(void) > > > { > > > int ret; > > > > > > + down(&vfio_perm_bits_sem); > > > + > > > + if (++vfio_pci_perm_bits_users > 1) { > > > + ret = 0; > > > + goto out; > > > + } > > > + > > > /* Basic config space */ > > > ret = init_pci_cap_basic_perm(&cap_perms[PCI_CAP_ID_BASIC]); > > > > > > @@ -1030,8 +1057,10 @@ int __init vfio_pci_init_perm_bits(void) > > > ecap_perms[PCI_EXT_CAP_ID_VNDR].writefn = vfio_raw_config_write; > > > > > > if (ret) > > > - vfio_pci_uninit_perm_bits(); > > > + vfio_pci_uninit_perm_bits_internal(); > > > > > > +out: > > > + up(&vfio_perm_bits_sem); > > > return ret; > > > } > > > > > > > Hi Yi, > > > > Sorry for slowness in providing feedback on this series. If we > > provided a vfio-pci-common module that vfio-pci and vfio-mdev-pci > > depend on, doesn't this entire problem go away? > > I checked previous email, export the common functions out of > vfio-pci module was proposed in RFC v2. But at that time, I didn't > propose to have a separate module. So I guess it may be just correct > way. Below is the reply at that time. > > https://lkml.org/lkml/2019/3/19/756 > > > I played a little bit > > with this in the crude patch below, it seems to work. To finish this, > > I think we'd move the function declarations out of the "private" header > > file and into one under include/linux, then we could also move > > vfio_mdev_pci.c to the samples directory like we intended originally. > > I know you had tried to link things from samples and it didn't work, > > but is the below a better attempt at resolving this? It commits us to > > exporting a bunch of functions, we'll need to decide whether that's a > > good idea. Thanks, > > I played with your patch and added a crude patch to move > vfio-mdev-pci to samples directory. I can see below errors with > either CONFIG_VFIO_PCI_COMMON=y and > CONFIG_SAMPLE_VFIO_MDEV_PCI=y, or > CONFIG_VFIO_PCI_COMMON=m and > CONFIG_SAMPLE_VFIO_MDEV_PCI=m. > > But CONFIG_VFIO_PCI_COMMON works well with CONFIG_VFIO_PCI... > > Kernel: arch/x86/boot/bzImage is ready (#88) > ERROR: "vfio_pci_fill_ids" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_err_handlers" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_reflck_attach" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_write" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_disable" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_reflck_put" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_refresh_config" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_set_power_state" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_enable" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_set_vga_decode" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_probe_power_state" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_mmap" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_ioctl" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > ERROR: "vfio_pci_read" [samples/vfio-mdev-pci/vfio-mdev-pci.ko] undefined! > scripts/Makefile.modpost:93: recipe for target '__modpost' failed > > So I'm afraid that it still cannot resolve the problem which we encountered > when trying to place vfio-mdev-pci in samples/. I'm not sure what we're doing differently (with your patch applied): $ grep VFIO ~/build/.config | grep -v ^# CONFIG_KVM_VFIO=y CONFIG_VFIO_IOMMU_TYPE1=m CONFIG_VFIO_VIRQFD=m CONFIG_VFIO=m CONFIG_VFIO_PCI_COMMON=m CONFIG_VFIO_PCI=m CONFIG_VFIO_PCI_VGA=y CONFIG_VFIO_PCI_MMAP=y CONFIG_VFIO_PCI_INTX=y CONFIG_VFIO_PCI_IGD=y CONFIG_VFIO_MDEV=m CONFIG_VFIO_MDEV_DEVICE=m CONFIG_SAMPLE_VFIO_MDEV_PCI=m $ make O=~/build -j36 > /dev/null && echo $? 0 $ grep VFIO ~/build/.config | grep -v ^# CONFIG_KVM_VFIO=y CONFIG_VFIO_IOMMU_TYPE1=y CONFIG_VFIO_VIRQFD=y CONFIG_VFIO=y CONFIG_VFIO_PCI_COMMON=y CONFIG_VFIO_PCI=y CONFIG_VFIO_PCI_VGA=y CONFIG_VFIO_PCI_MMAP=y CONFIG_VFIO_PCI_INTX=y CONFIG_VFIO_PCI_IGD=y CONFIG_VFIO_MDEV=m CONFIG_VFIO_MDEV_DEVICE=m $ make O=~/build -j36 > /dev/null && echo $? 0 $ grep VFIO ~/build/.config | grep -v ^# CONFIG_KVM_VFIO=y CONFIG_VFIO_IOMMU_TYPE1=y CONFIG_VFIO_VIRQFD=m CONFIG_VFIO=y CONFIG_VFIO_PCI_COMMON=m CONFIG_VFIO_PCI=m CONFIG_VFIO_PCI_VGA=y CONFIG_VFIO_PCI_MMAP=y CONFIG_VFIO_PCI_INTX=y CONFIG_VFIO_PCI_IGD=y CONFIG_VFIO_MDEV=m CONFIG_VFIO_MDEV_DEVICE=m $ make O=~/build -j36 > /dev/null && echo $? 0 > ================= [the crude patch] ================= > From fa860ff15ab188481141f7bd2b9cb3a1d500f24d Mon Sep 17 00:00:00 2001 > From: Liu Yi L <yi.l.liu@xxxxxxxxx> > Date: Sun, 15 Dec 2019 19:16:54 +0800 > Subject: [PATCH] vfio/pci/sample: move vfio-pci-mdev to samples > > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> > --- > drivers/vfio/pci/Makefile | 2 - > drivers/vfio/pci/vfio_mdev_pci.c | 421 ---------------------------------- > drivers/vfio/pci/vfio_pci.c | 2 +- > drivers/vfio/pci/vfio_pci_common.c | 2 +- > drivers/vfio/pci/vfio_pci_config.c | 2 +- > drivers/vfio/pci/vfio_pci_igd.c | 2 +- > drivers/vfio/pci/vfio_pci_intrs.c | 2 +- > drivers/vfio/pci/vfio_pci_nvlink2.c | 2 +- > drivers/vfio/pci/vfio_pci_private.h | 228 ------------------ > drivers/vfio/pci/vfio_pci_rdwr.c | 2 +- > include/linux/vfio_pci_private.h | 228 ++++++++++++++++++ Of course this would not be "private" if this is the direction we decide to go. Potentially there are still things private to vfio-pci-common that we'd leave in the drivers directory though. I'm not entirely thrilled to expose the objects outside of vfio-pci, but potentially if vfio-pci had a mechanism to choose an alternate vfio_device_ops that provided vendor mediation extension when calling vfio_add_group_dev(), and common code was sharable to vendor drivers, it might clean up the interface Yan is proposing for adding migration to non-mdev devices. Thanks, Alex
