From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:50011) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gmOjm-0007CI-T0 for qemu-devel@nongnu.org; Wed, 23 Jan 2019 15:03:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gmOdJ-0002d6-Lo for qemu-devel@nongnu.org; Wed, 23 Jan 2019 14:56:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50924) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gmOdD-0002Xg-R4 for qemu-devel@nongnu.org; Wed, 23 Jan 2019 14:56:17 -0500 Date: Wed, 23 Jan 2019 12:56:08 -0700 From: Alex Williamson Message-ID: <20190123125608.439c31da@w520.home> In-Reply-To: References: <20190123120422.36273dd1@w520.home> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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: Knut Omang Cc: "Michael S . Tsirkin" , Stefan Hajnoczi , Elijah Shakkour , qemu-devel@nongnu.org, Tal Attaly On Wed, 23 Jan 2019 20:46:14 +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". 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. > > I think my intention way back when I implemented this was to provide it as a skeleton > for further detailing later, I use it with ectrl_words = 0 in the root port. > > > > + 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. > > I must admit I haven't really dived deep here - I just set the cap bits that one of my > servers sets for it's root ports - this is the one I used as model: > > 00:02.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 1 (rev > 22) (prog-if 00 [Normal decode]) > 00:02.0 0604: 8086:3409 (rev 22) > > > > + 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. > > I agree - I'll implement it, > thanks! > > Knut > > > > > > + /* Make CTRL register writable */ > > > + memset(dev->wmask + offset + PCI_ACS_CTRL, 0xff, 2); While you're at it, it doesn't make sense to set unimplemented control bits as writable, this should match the bits set in the capabilities register. Thanks, Alex > > > +} > > > 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 */ > > > >