Re: [Qemu-devel] [PATCH v5 1/2] pcie: Add a simple PCIe ACS (Access Control Services) helper function

[Knut Omang]

On Sat, 2019-02-16 at 11:17 -0700, Alex Williamson wrote:
> On Sat, 16 Feb 2019 17:51:11 +0100
> Knut Omang <address@hidden> wrote:
> 
> > Implementing an ACS capability on downstream ports and multifunction
> > endpoints indicates isolation and IOMMU visibility to a finer
> > granularity. This creates smaller IOMMU groups in the guest and thus
> > more flexibility in assigning endpoints to guest userspace or an L2
> > guest.
> > 
> > Signed-off-by: Knut Omang <address@hidden>
> > ---
> >  hw/pci/pcie.c              | 39 +++++++++++++++++++++++++++++++++++++++-
> >  include/hw/pci/pcie.h      |  6 ++++++-
> >  include/hw/pci/pcie_regs.h |  4 ++++-
> >  3 files changed, 49 insertions(+)
> > 
> > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> > index 230478f..6afc37a 100644
> > --- a/hw/pci/pcie.c
> > +++ b/hw/pci/pcie.c
> > @@ -906,3 +906,42 @@ void pcie_ats_init(PCIDevice *dev, uint16_t offset)
> >  
> >      pci_set_word(dev->wmask + dev->exp.ats_cap + PCI_ATS_CTRL, 0x800f);
> >  }
> > +
> > +/* ACS (Access Control Services) */
> > +void pcie_acs_init(PCIDevice *dev, uint16_t offset)
> > +{
> > +    bool is_downstream = pci_is_express_downstream_port(dev);
> > +    uint16_t cap_bits = 0;
> > +
> > +    /* For endpoints, only multifunction devs may have an ACS capability: 
> > */
> > +    assert(is_downstream ||
> > +           (dev->cap_present & QEMU_PCI_CAP_MULTIFUNCTION) ||
> > +           PCI_FUNC(dev->devfn));
> > +
> > +    pcie_add_capability(dev, PCI_EXT_CAP_ID_ACS, PCI_ACS_VER, offset,
> > +                        PCI_ACS_SIZEOF);
> > +    dev->exp.acs_cap = offset;
> > +
> > +    if (is_downstream) {
> > +        /* Downstream ports must implement SV, TB, RR, CR, and UF (with
> > +         * caveats on the latter three that we ignore for simplicity).
> > +         * Endpoints may also implement a subset of ACS capabilities,
> > +         * but these are optional if the endpoint does not support
> > +         * peer-to-peer between functions and thus omitted here.
> > +         * Downstream switch ports must also implement DT, while this
> > +         * is optional for root ports, so we set that as well:
> > +         */
> 
> Again...
> https://git.qemu.org/?p=qemu.git;a=blob;f=CODING_STYLE;hb=HEAD#l127
> 
> Personally I'd add DT in the original list rather than mention is
> separately, the caveats are pretty similar.

Sorry, I know - just overlooked it and forgot to re-check the style again.
Just sent v6.

Knut

> > +        cap_bits = PCI_ACS_SV | PCI_ACS_TB | PCI_ACS_RR |
> > +            PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_DT;
> > +    }
> > +
> > +    pci_set_word(dev->config + offset + PCI_ACS_CAP, cap_bits);
> > +    pci_set_word(dev->wmask + offset + PCI_ACS_CTRL, cap_bits);
> > +}
> > +
> > +void pcie_acs_reset(PCIDevice *dev)
> > +{
> > +    if (dev->exp.acs_cap) {
> > +        pci_set_word(dev->config + dev->exp.acs_cap + PCI_ACS_CTRL, 0);
> > +    }
> > +}
> > diff --git a/include/hw/pci/pcie.h b/include/hw/pci/pcie.h
> > index 5b82a0d..e30334d 100644
> > --- a/include/hw/pci/pcie.h
> > +++ b/include/hw/pci/pcie.h
> > @@ -79,6 +79,9 @@ struct PCIExpressDevice {
> >  
> >      /* Offset of ATS capability in config space */
> >      uint16_t ats_cap;
> > +
> > +    /* ACS */
> > +    uint16_t acs_cap;
> >  };
> >  
> >  #define COMPAT_PROP_PCP "power_controller_present"
> > @@ -128,6 +131,9 @@ void pcie_add_capability(PCIDevice *dev,
> >                           uint16_t offset, uint16_t size);
> >  void pcie_sync_bridge_lnk(PCIDevice *dev);
> >  
> > +void pcie_acs_init(PCIDevice *dev, uint16_t offset);
> > +void pcie_acs_reset(PCIDevice *dev);
> > +
> >  void pcie_ari_init(PCIDevice *dev, uint16_t offset, uint16_t nextfn);
> >  void pcie_dev_ser_num_init(PCIDevice *dev, uint16_t offset, uint64_t 
> > ser_num);
> >  void pcie_ats_init(PCIDevice *dev, uint16_t offset);
> > diff --git a/include/hw/pci/pcie_regs.h b/include/hw/pci/pcie_regs.h
> > index ad4e780..1db86b0 100644
> > --- a/include/hw/pci/pcie_regs.h
> > +++ b/include/hw/pci/pcie_regs.h
> > @@ -175,4 +175,8 @@ typedef enum PCIExpLinkWidth {
> >                                           PCI_ERR_COR_INTERNAL |         \
> >                                           PCI_ERR_COR_HL_OVERFLOW)
> >  
> > +/* ACS */
> > +#define PCI_ACS_VER                     0x1
> > +#define PCI_ACS_SIZEOF                  8
> > +
> >  #endif /* QEMU_PCIE_REGS_H */
>