On Thu, Nov 25, 2021 at 01:02:49PM +0200, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com>
>
> There are three originators for the PCI configuration space access:
> 1. The domain that owns physical host bridge: MMIO handlers are
> there so we can update vPCI register handlers with the values
> written by the hardware domain, e.g. physical view of the registers
> vs guest's view on the configuration space.
> 2. Guest access to the passed through PCI devices: we need to properly
> map virtual bus topology to the physical one, e.g. pass the configuration
> space access to the corresponding physical devices.
> 3. Emulated host PCI bridge access. It doesn't exist in the physical
> topology, e.g. it can't be mapped to some physical host bridge.
> So, all access to the host bridge itself needs to be trapped and
> emulated.
I'm kind of lost in this commit message. You are just adding a
translate function in order for domUs to translate from virtual SBDF
to the physical SBDF of the device. I realize you do that based on
whether 'bridge' is set or not, so I assume this is just a way to
signal whether the domain is a hardware domain or not. Ie:
!!bridge == is_hardware_domain(v->domain).
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com>
> ---
> Since v4:
> - indentation fixes
> - constify struct domain
> - updated commit message
> - updates to the new locking scheme (pdev->vpci_lock)
> Since v3:
> - revisit locking
> - move code to vpci.c
> Since v2:
> - pass struct domain instead of struct vcpu
> - constify arguments where possible
> - gate relevant code with CONFIG_HAS_VPCI_GUEST_SUPPORT
> New in v2
> ---
> xen/arch/arm/vpci.c | 18 ++++++++++++++++++
> xen/drivers/vpci/vpci.c | 27 +++++++++++++++++++++++++++
> xen/include/xen/vpci.h | 1 +
> 3 files changed, 46 insertions(+)
>
> diff --git a/xen/arch/arm/vpci.c b/xen/arch/arm/vpci.c
> index 8e801f275879..3d134f42d07e 100644
> --- a/xen/arch/arm/vpci.c
> +++ b/xen/arch/arm/vpci.c
> @@ -41,6 +41,15 @@ static int vpci_mmio_read(struct vcpu *v, mmio_info_t
> *info,
> /* data is needed to prevent a pointer cast on 32bit */
> unsigned long data;
>
> +#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
> + /*
> + * For the passed through devices we need to map their virtual SBDF
> + * to the physical PCI device being passed through.
> + */
> + if ( !bridge && !vpci_translate_virtual_device(v->domain, &sbdf) )
> + return 1;
I'm unsure what returning 1 implies for Arm here, but you likely need
to set '*r = ~0ul;'.
> +#endif
> +
> if ( vpci_ecam_read(sbdf, ECAM_REG_OFFSET(info->gpa),
> 1U << info->dabt.size, &data) )
> {
> @@ -59,6 +68,15 @@ static int vpci_mmio_write(struct vcpu *v, mmio_info_t
> *info,
> struct pci_host_bridge *bridge = p;
> pci_sbdf_t sbdf = vpci_sbdf_from_gpa(bridge, info->gpa);
>
> +#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
> + /*
> + * For the passed through devices we need to map their virtual SBDF
> + * to the physical PCI device being passed through.
> + */
> + if ( !bridge && !vpci_translate_virtual_device(v->domain, &sbdf) )
> + return 1;
> +#endif
> +
> return vpci_ecam_write(sbdf, ECAM_REG_OFFSET(info->gpa),
> 1U << info->dabt.size, r);
> }
> diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
> index c2fb4d4db233..bdc8c63f73fa 100644
> --- a/xen/drivers/vpci/vpci.c
> +++ b/xen/drivers/vpci/vpci.c
> @@ -195,6 +195,33 @@ static void vpci_remove_virtual_device(struct domain *d,
> pdev->vpci->guest_sbdf.sbdf = ~0;
> }
>
> +/*
> + * Find the physical device which is mapped to the virtual device
> + * and translate virtual SBDF to the physical one.
> + */
> +bool vpci_translate_virtual_device(const struct domain *d, pci_sbdf_t *sbdf)
> +{
> + struct pci_dev *pdev;
> +
I would add:
ASSERT(!is_hardware_domain(d));
To make sure this is not used for the hardware domain.
> + for_each_pdev( d, pdev )
> + {
> + bool found;
> +
> + spin_lock(&pdev->vpci_lock);
> + found = pdev->vpci && (pdev->vpci->guest_sbdf.sbdf == sbdf->sbdf);
> + spin_unlock(&pdev->vpci_lock);
> +
> + if ( found )
> + {
> + /* Replace guest SBDF with the physical one. */
> + *sbdf = pdev->sbdf;
> + return true;
> + }
> + }
> +
> + return false;
> +}
> +
> /* Notify vPCI that device is assigned to guest. */
> int vpci_assign_device(struct domain *d, struct pci_dev *pdev)
> {
> diff --git a/xen/include/xen/vpci.h b/xen/include/xen/vpci.h
> index e5258bd7ce90..21d76929391f 100644
> --- a/xen/include/xen/vpci.h
> +++ b/xen/include/xen/vpci.h
> @@ -280,6 +280,7 @@ static inline void vpci_cancel_pending_locked(struct
> pci_dev *pdev)
> /* Notify vPCI that device is assigned/de-assigned to/from guest. */
> int vpci_assign_device(struct domain *d, struct pci_dev *pdev);
> int vpci_deassign_device(struct domain *d, struct pci_dev *pdev);
> +bool vpci_translate_virtual_device(const struct domain *d, pci_sbdf_t *sbdf);
> #else
> static inline int vpci_assign_device(struct domain *d, struct pci_dev *pdev)
> {
If you add a dummy vpci_translate_virtual_device helper that returns
false unconditionally here you could drop the #ifdefs in arm/vpci.c
AFAICT.
Thanks, Roger.
