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From: Boqun Feng <boqun.feng@gmail.com>
To: Bjorn Helgaas <bhelgaas@google.com>,
	Arnd Bergmann <arnd@arndb.de>, Marc Zyngier <maz@kernel.org>
Cc: "Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	"Haiyang Zhang" <haiyangz@microsoft.com>,
	"Stephen Hemminger" <sthemmin@microsoft.com>,
	"Wei Liu" <wei.liu@kernel.org>,
	"Dexuan Cui" <decui@microsoft.com>,
	"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	"Rob Herring" <robh@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
	linux-pci@vger.kernel.org,
	"Sunil Muthuswamy" <sunilmut@microsoft.com>,
	"Mike Rapoport" <rppt@kernel.org>
Subject: [RFC v5 1/8] PCI: Introduce domain_nr in pci_host_bridge
Date: Tue, 20 Jul 2021 21:44:22 +0800	[thread overview]
Message-ID: <20210720134429.511541-2-boqun.feng@gmail.com> (raw)
In-Reply-To: <20210720134429.511541-1-boqun.feng@gmail.com>

Currently we retrieve the PCI domain number of the host bridge from the
bus sysdata (or pci_config_window if PCI_DOMAINS_GENERIC=y). Actually
we have the information at PCI host bridge probing time, and it makes
sense that we store it into pci_host_bridge. One benefit of doing so is
the requirement for supporting PCI on Hyper-V for ARM64, because the
host bridge of Hyper-V doesn't have pci_config_window, whereas ARM64 is
a PCI_DOMAINS_GENERIC=y arch, so we cannot retrieve the PCI domain
number from pci_config_window on ARM64 Hyper-V guest.

As the preparation for ARM64 Hyper-V PCI support, we introduce the
domain_nr in pci_host_bridge and a sentinel value to allow drivers to
set domain numbers properly at probing time. Currently
CONFIG_PCI_DOMAINS_GENERIC=y archs are only users of this
newly-introduced field.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
 drivers/pci/probe.c |  6 +++++-
 include/linux/pci.h | 10 ++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 79177ac37880..60c50d4f156f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -594,6 +594,7 @@ static void pci_init_host_bridge(struct pci_host_bridge *bridge)
 	bridge->native_pme = 1;
 	bridge->native_ltr = 1;
 	bridge->native_dpc = 1;
+	bridge->domain_nr = PCI_DOMAIN_NR_NOT_SET;
 
 	device_initialize(&bridge->dev);
 }
@@ -898,7 +899,10 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 	bus->ops = bridge->ops;
 	bus->number = bus->busn_res.start = bridge->busnr;
 #ifdef CONFIG_PCI_DOMAINS_GENERIC
-	bus->domain_nr = pci_bus_find_domain_nr(bus, parent);
+	if (bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET)
+		bus->domain_nr = pci_bus_find_domain_nr(bus, parent);
+	else
+		bus->domain_nr = bridge->domain_nr;
 #endif
 
 	b = pci_find_bus(pci_domain_nr(bus), bridge->busnr);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 540b377ca8f6..2c413a64d168 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -526,6 +526,15 @@ static inline int pci_channel_offline(struct pci_dev *pdev)
 	return (pdev->error_state != pci_channel_io_normal);
 }
 
+/*
+* Currently in ACPI spec, for each PCI host bridge, PCI Segment Group number is
+* limited to a 16-bit value, therefore (int)-1 is not a valid PCI domain number,
+* and can be used as a sentinel value indicating >domain_nr is not set by the
+* driver (and CONFIG_PCI_DOMAINS_GENERIC=y archs will set it with
+* pci_bus_find_domain_nr()).
+*/
+#define PCI_DOMAIN_NR_NOT_SET (-1)
+
 struct pci_host_bridge {
 	struct device	dev;
 	struct pci_bus	*bus;		/* Root bus */
@@ -533,6 +542,7 @@ struct pci_host_bridge {
 	struct pci_ops	*child_ops;
 	void		*sysdata;
 	int		busnr;
+	int		domain_nr;
 	struct list_head windows;	/* resource_entry */
 	struct list_head dma_ranges;	/* dma ranges resource list */
 	u8 (*swizzle_irq)(struct pci_dev *, u8 *); /* Platform IRQ swizzler */
-- 
2.30.2


  reply	other threads:[~2021-07-20 14:02 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-20 13:44 [RFC v5 0/8] PCI: hv: Support host bridge probing on ARM64 Boqun Feng
2021-07-20 13:44 ` Boqun Feng [this message]
2021-07-20 22:49   ` [RFC v5 1/8] PCI: Introduce domain_nr in pci_host_bridge Bjorn Helgaas
2021-07-21  0:57     ` Boqun Feng
2021-07-20 13:44 ` [RFC v5 2/8] PCI: Support populating MSI domains of root buses via bridges Boqun Feng
2021-07-20 13:44 ` [RFC v5 3/8] arm64: PCI: Restructure pcibios_root_bridge_prepare() Boqun Feng
2021-07-20 13:44 ` [RFC v5 4/8] arm64: PCI: Support root bridge preparation for Hyper-V Boqun Feng
2021-07-20 13:44 ` [RFC v5 5/8] PCI: hv: Generify PCI probing Boqun Feng
2021-07-20 13:44 ` [RFC v5 6/8] PCI: hv: Set ->domain_nr of pci_host_bridge at probing time Boqun Feng
2021-07-20 13:44 ` [RFC v5 7/8] PCI: hv: Set up MSI domain at bridge " Boqun Feng
2021-07-20 13:44 ` [RFC v5 8/8] PCI: hv: Turn on the host bridge probing on ARM64 Boqun Feng
2021-07-20 14:38   ` Marc Zyngier
2021-07-20 14:59     ` Boqun Feng
2021-07-20 15:53       ` Marc Zyngier

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