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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?83ammAkQQzD4LgmC/nFOYJiRS9gxLSsClB2UzVHtrdIxZBSVNGY5Ye4NaTzd?= =?us-ascii?Q?OzqIt8h0EvaqSMFQtw1KoIkaFsHUn93BQzgkwv+fQ+bmx3USpwiKnqRQiJfl?= =?us-ascii?Q?9ezDhBO3cNePQK//OQBlgkSNtogucSq/3vNVnYcgySSMH8+oNs0XVoJILWi3?= =?us-ascii?Q?JYe9RQ3o5bhzz27cuWYvj9sKohZ2p2RNRyzw1QsdoVJ85nnhJKE1C+pAlpW3?= =?us-ascii?Q?kv6cwHJblEWsj0Ds4PhOEvNo6y39jCn8VqRlxrQCZjWZ+gwY8eFv9/iM78D3?= =?us-ascii?Q?/gFAWCKPdAbky//3lGblXKCjHyHydnQA5gzfn5Es2e+vGSnSDpERclVY6apA?= =?us-ascii?Q?E+aZZEZlWifwyvpz8Ybc6SbMdUd5s+0zoPKIEEluHS6LnnQ+NW2tAwq6GuTJ?= =?us-ascii?Q?Ui/JnPNCZoAUSnaKBPGG1CVC9bocEiZe3ZNMqq+kUl+fn0zD3YN1GdoGo85y?= =?us-ascii?Q?srul0rO8iyb8ozdAgukTgMvcjPAaW2+jCzzXh8XGP8LOJbxbLAi3FNO+EWVR?= =?us-ascii?Q?cORZGyznGnCGnqTLIAFgtaCZw0HdCa5uJ26LhQgEATnWQW86XXQqWqTqFXhy?= =?us-ascii?Q?vANs4z3nQjZNFIb2muREcnt+iinZVB01wx+0jSti4nQDa+NML6z8+tHvXP2t?= =?us-ascii?Q?TyUI10iltYF4fxu1olWoUlz73mFCnrucmcPOjEFGx9neR/ADbd9NlQxNo90Y?= =?us-ascii?Q?pTUV6sRE2Bi3lwL2MSblOS9u8VFPBpKGIz5bAbBn1RyWnqisB3TGfn/lW/C3?= =?us-ascii?Q?HD4R4hbtPhhN0oCK7QTFa+KFz+Y9vfyEdvyPzYUranARAoww7tVOu2Xu3MWA?= =?us-ascii?Q?zHHhFk5CsZEaHOq1Tfrf2ahWlmNrunWaQWv3sBB2I/Z1H7AH6U7vN9pIV+7L?= =?us-ascii?Q?KrOaORpPc+BJedkp4M6rLVHPzWwz5SU3qYTm0IbB3nb315yAYszHW6nOYk+a?= =?us-ascii?Q?qP1psNt9aJhe4nkqat2colaQsc9s1POliA+1jF+6qBHXBnGTP7aOp9/211BQ?= =?us-ascii?Q?n2hvhfDPGkeJONMraNv6z87jtRL++rqeEqiw7CahQdD/X8G44HSwJB1Y9OQH?= =?us-ascii?Q?IPzdbG23rTwJkK2hH9UCW98bbc1EA6+aBQXIZkP3mt2qDe9dd+5o1DdFvjmW?= =?us-ascii?Q?sKsf/9CqJh75Zpt7pWIojYF1yCuIqwnzj2Ako5LzSaqT1+hjPoBTnDHN4uqr?= =?us-ascii?Q?nCH0oe33vyIxQXpcbqLtRU9Zi0E7k9pJMVdxwxF/X3VvIkmu3Gd+m2TwHLcd?= =?us-ascii?Q?1tPo/hHk/R6BTkXOhO+neU05Y0PnwM4fuGaltbonJAQkQBBf2yMNQB7tH+Bl?= =?us-ascii?Q?scFgDLf39bLcjWDoAapjl15O84vZLXaq2JEy+Erkhz/lqbbGA3vbzzsiFI1D?= =?us-ascii?Q?kOw2swSWLJ6JrJ6omMHtIcPJps9lYygmclXD4Up//U9eCiMoPD0XCt0C2jp8?= =?us-ascii?Q?+hn6VEEvDuWnuhvfLicXNlqa8wk1IlRsP2Dfoqn5mKCBszzJHfGsZFHewi42?= =?us-ascii?Q?DT6z6AR6YJt+Jq32hFwKvT+07NE+d6w8AjMBmN/beV/Zj/V+rkHEmACgYi4b?= =?us-ascii?Q?GZfOBbC9LeVxdNSOJx1VSbL1VqCC2wDeRhbOM3Ynq+tX5UTwmVTjjkfa9Jzh?= =?us-ascii?Q?Xg=3D=3D?= X-OriginatorOrg: vmware.com X-MS-Exchange-CrossTenant-Network-Message-Id: 763720c7-54ba-4c96-6a5e-08d9f6c2b33a X-MS-Exchange-CrossTenant-AuthSource: PH0PR05MB8703.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Feb 2022 11:50:34.2392 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: A3zZi3iOT/iSsd023DCJG+tPM8HGo7O4S+UAB3vAtBypbX8KtWDI+QqNSUH0Po7p3jjqje7s1/oR2xKQFeNYow== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR05MB7334 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Vikash Bansal In the current implementation, the PCI capability list is parsed from the beginning to find each capability, which results in a large number of redundant PCI reads. Instead, we can parse the complete list just once, store it in the pci_dev structure, and get the offset of each capability directly from the pci_dev structure. This implementation improves pci devices initialization time by ~2-3% (from 270ms to 261ms) in case of bare metal and 7-8% (From 201ms to 184ms) in case of VM running on ESXi. It also adds a memory overhead of 20bytes (value of PCI_CAP_ID_MAX) per PCI device. Ran pahole for pci_dev structure. This patch is not adding any padding bytes. Signed-off-by: Vikash Bansal Signed-off-by: Ajay Kaher --- Changes in v3: - Added check before access cap_off from pci_find_capability(). - Moved declaration of pci_find_all_capabilities() to drivers/pci/pci.h. Changes in v2: - Ran pahole tool. - Modified comments to add "clock time". - Removed comments before call to pci_find_all_capabilities. --- drivers/pci/pci.c | 44 +++++++++++++++++++++++++++++++++++++------- drivers/pci/pci.h | 1 + drivers/pci/probe.c | 1 + include/linux/pci.h | 1 + 4 files changed, 40 insertions(+), 7 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 3d2fb39..cf54811 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -469,6 +469,40 @@ static u8 __pci_bus_find_cap_start(struct pci_bus *bus, } /** + * pci_find_all_capabilities - Read all capabilities + * @dev: the PCI device + * + * Read all capabilities and store offsets in cap_off + * array in pci_dev structure. + */ +void pci_find_all_capabilities(struct pci_dev *dev) +{ + int ttl = PCI_FIND_CAP_TTL; + u16 ent; + u8 pos; + u8 id; + + pos = __pci_bus_find_cap_start(dev->bus, dev->devfn, dev->hdr_type); + if (!pos) + return; + pci_bus_read_config_byte(dev->bus, dev->devfn, pos, &pos); + while (ttl--) { + if (pos < 0x40) + break; + pos &= ~3; + pci_bus_read_config_word(dev->bus, dev->devfn, pos, &ent); + id = ent & 0xff; + if (id == 0xff) + break; + + /* Read first instance of capability */ + if (!(dev->cap_off[id])) + dev->cap_off[id] = pos; + pos = (ent >> 8); + } +} + +/** * pci_find_capability - query for devices' capabilities * @dev: PCI device to query * @cap: capability code @@ -489,13 +523,9 @@ static u8 __pci_bus_find_cap_start(struct pci_bus *bus, */ u8 pci_find_capability(struct pci_dev *dev, int cap) { - u8 pos; - - pos = __pci_bus_find_cap_start(dev->bus, dev->devfn, dev->hdr_type); - if (pos) - pos = __pci_find_next_cap(dev->bus, dev->devfn, pos, cap); - - return pos; + if(cap >= PCI_CAP_ID_MAX) + return 0; + return dev->cap_off[cap]; } EXPORT_SYMBOL(pci_find_capability); diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 3d60cab..3cb70d5 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -87,6 +87,7 @@ bool pci_bridge_d3_possible(struct pci_dev *dev); void pci_bridge_d3_update(struct pci_dev *dev); void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev); void pci_bridge_reconfigure_ltr(struct pci_dev *dev); +void pci_find_all_capabilities(struct pci_dev *dev); static inline void pci_wakeup_event(struct pci_dev *dev) { diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 087d365..d75e1fa 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1839,6 +1839,7 @@ int pci_setup_device(struct pci_dev *dev) dev->hdr_type = hdr_type & 0x7f; dev->multifunction = !!(hdr_type & 0x80); dev->error_state = pci_channel_io_normal; + pci_find_all_capabilities(dev); set_pcie_port_type(dev); pci_set_of_node(dev); diff --git a/include/linux/pci.h b/include/linux/pci.h index 18a75c8..bd61cee 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -326,6 +326,7 @@ struct pci_dev { unsigned int class; /* 3 bytes: (base,sub,prog-if) */ u8 revision; /* PCI revision, low byte of class word */ u8 hdr_type; /* PCI header type (`multi' flag masked out) */ + u8 cap_off[PCI_CAP_ID_MAX]; /* Offsets of all pci capabilities */ #ifdef CONFIG_PCIEAER u16 aer_cap; /* AER capability offset */ struct aer_stats *aer_stats; /* AER stats for this device */ -- 2.7.4