Re: [RFC v5 8/8] PCI: hv: Turn on the host bridge probing on ARM64

On Tue, Jul 20, 2021 at 03:38:26PM +0100, Marc Zyngier wrote:

On Tue, 20 Jul 2021 14:44:29 +0100,
Boqun Feng [off-list ref] wrote:

quoted

Now we have everything we need, just provide a proper sysdata type for
the bus to use on ARM64 and everything else works.

Signed-off-by: Boqun Feng <redacted>
---
 drivers/pci/controller/pci-hyperv.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index e6276aaa4659..62dbe98d1fe1 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c

@@ -40,6 +40,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/pci-ecam.h>
 #include <linux/delay.h>
 #include <linux/semaphore.h>
 #include <linux/irqdomain.h>

@@ -448,7 +449,11 @@ enum hv_pcibus_state {
 };
 
 struct hv_pcibus_device {
+#ifdef CONFIG_X86
 	struct pci_sysdata sysdata;
+#elif defined(CONFIG_ARM64)
+	struct pci_config_window sysdata;
+#endif

Am I the only one who find this rather odd? Nothing ever populates
this data structure on arm64, and its only purpose seems to serve as
an anchor to retrieve the hbus via container_of().

This field will also be used as the ->sysdata of pci_bus and
pci_host_bridge, and some of the PCI core code touches. Although I made
this field as all zeroed and make sure PCI core can handle (patch #4).

If that's indeed the case, I'd rather see an arch-specific to_hbus()
helper that uses another (preexisting) field as the anchor for arm64.

I did a quick look, but I didn't find another field works: the field
needs to be placed inside hv_pcibus_device and the address can be
retrieved via pci_bus. I'm open to any suggestion in case that I missed
something.

Regards,
Boqun

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.