From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:46153) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gmOPd-00033S-6p for qemu-devel@nongnu.org; Wed, 23 Jan 2019 14:42:16 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gmOLa-0006z2-4Z for qemu-devel@nongnu.org; Wed, 23 Jan 2019 14:38:03 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:52378) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gmOLZ-0006yn-R0 for qemu-devel@nongnu.org; Wed, 23 Jan 2019 14:38:02 -0500 Message-ID: <6ed489447d18e868519f52d526bd1e522ac7f4a7.camel@oracle.com> From: Knut Omang Date: Wed, 23 Jan 2019 20:37:50 +0100 In-Reply-To: <20190123123258.1d97f14a@w520.home> References: <20190123120422.36273dd1@w520.home> <20190123123258.1d97f14a@w520.home> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1/2] pcie: Add a simple PCIe ACS (Access Control Services) helper function List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: qemu-devel@nongnu.org, "Michael S . Tsirkin" , Marcel Apfelbaum , Tal Attaly , Elijah Shakkour , Stefan Hajnoczi On Wed, 2019-01-23 at 12:32 -0700, Alex Williamson wrote: > On Wed, 23 Jan 2019 20:14:07 +0100 > Knut Omang wrote: > > > On Wed, 2019-01-23 at 12:04 -0700, Alex Williamson wrote: > > > On Wed, 23 Jan 2019 19:27:59 +0100 > > > Knut Omang wrote: > > > > > > > Add a helper function to add PCIe capability for Access Control Services (ACS) > > > > ACS support in the associated root port is a prerequisite to be able to do useful > > > > passthrough with VFIO without Alex Williamson's pcie_acs_override kernel patch. > > > > > > Define "useful". > > > > Hmm - just that without the patches, the root port itself > > also gets assigned to the same group, which seemed problematic to me > > (without any further testing than just binding/unbinding to VFIO) > > vfio-pci binding rules only apply to endpoints. A root port lacking > ACS will include all devices downstream of it in the IOMMU group, and > potentially sibling functions, and devices downstream of those, but it > doesn't absolutely preclude L2 assignment, or L1 userspace usage, > which is already widely used. It simply means that all the endpoints > within that group need to be bound to vfio-pci and can only have a > single owner. Thanks, I see, that makes sense - I'll moderate my language! Thanks, Knut > > Alex > > > > We can certainly still assign single function PFs to > > > an L2 guest, or multi-function so long as all the functions are > > > assigned. I won't deny that it's problematic, but it's a virtual > > > topology that can be adjusted, so I think this is overstating things a > > > bit. > > > > > > > Signed-off-by: Knut Omang > > > > --- > > > > hw/pci/pcie.c | 14 ++++++++++++++ > > > > include/hw/pci/pcie.h | 1 + > > > > include/hw/pci/pcie_regs.h | 4 ++++ > > > > 3 files changed, 19 insertions(+) > > > > > > > > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c > > > > index 230478f..18feff5 100644 > > > > --- a/hw/pci/pcie.c > > > > +++ b/hw/pci/pcie.c > > > > @@ -906,3 +906,17 @@ void pcie_ats_init(PCIDevice *dev, uint16_t offset) > > > > > > > > pci_set_word(dev->wmask + dev->exp.ats_cap + PCI_ATS_CTRL, 0x800f); > > > > } > > > > + > > > > +/* Add an ACS (Access Control Services) capability */ > > > > +void pcie_acs_init(PCIDevice *dev, uint16_t offset, uint8_t egress_ctrl_vec_sz) > > > > +{ > > > > + int ectrl_words = (egress_ctrl_vec_sz + 31) & ~31; > > > > + pcie_add_capability(dev, PCI_EXT_CAP_ID_ACS, PCI_ACS_VER, > > > > + offset, PCI_ACS_SIZEOF + ectrl_words); > > > > > > The egress control vector is only valid if the egress control > > > capability is enabled, which is not set below, so this just seems to > > > waste config space and introduces a meaningless function arg. > > > > > > > + pci_set_word(dev->config + offset + PCI_ACS_CAP, > > > > + PCI_ACS_SV | PCI_ACS_TB | PCI_ACS_RR | PCI_ACS_CR | > PCI_ACS_UF); > > > > > > Some of these bits are only valid for downstream ports, it would > > > violate the spec to set them on and endpoint. > > > > > > > + pci_set_word(dev->config + offset + PCI_ACS_CTRL, > > > > + PCI_ACS_SV | PCI_ACS_TB | PCI_ACS_RR | PCI_ACS_CR | > PCI_ACS_UF); > > > > > > The default values of the control register bits is zero, so we > > > shouldn't be setting it here and we should have a reset hook to clear > > > it. > > > > > > > + /* Make CTRL register writable */ > > > > + memset(dev->wmask + offset + PCI_ACS_CTRL, 0xff, 2); > > > > +} > > > > diff --git a/include/hw/pci/pcie.h b/include/hw/pci/pcie.h > > > > index 5b82a0d..c2da148 100644 > > > > --- a/include/hw/pci/pcie.h > > > > +++ b/include/hw/pci/pcie.h > > > > @@ -129,6 +129,7 @@ void pcie_add_capability(PCIDevice *dev, > > > > void pcie_sync_bridge_lnk(PCIDevice *dev); > > > > > > > > void pcie_ari_init(PCIDevice *dev, uint16_t offset, uint16_t nextfn); > > > > +void pcie_acs_init(PCIDevice *dev, uint16_t offset, uint8_t egress_ctrl_vec_sz); > > > > 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..5e7409c 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 0x2 > > > > +#define PCI_ACS_SIZEOF 8 > > > > + > > > > #endif /* QEMU_PCIE_REGS_H */ > > > > > >