Re: [PATCH 2/6] pci: Scan all functions when probing while running over Jailhouse

[Jan Kiszka]

On 2018-02-22 21:57, Bjorn Helgaas wrote:
> On Mon, Jan 22, 2018 at 07:12:46AM +0100, Jan Kiszka wrote:
>> From: Jan Kiszka 
>>
>> PCI and PCIBIOS probing only scans devices at function number 0/8/16/...
>> Subdevices (e.g. multiqueue) have function numbers which are not a
>> multiple of 8.
> 
> Suggested text:
> 
>   Per PCIe r4.0, sec 7.5.1.1.9, multi-function devices are required to
>   have a function 0.  Therefore, Linux scans for devices at function 0
>   (devfn 0/8/16/...) and only scans for other functions if function 0
>   has its Multi-Function Device bit set or ARI or SR-IOV indicate
>   there are more functions.
>   
>   The Jailhouse hypervisor may pass individual functions of a
>   multi-function device to a guest without passing function 0, which
>   means a Linux guest won't find them.
> 
>   Change Linux PCI probing so it scans all function numbers when
>   running as a guest over Jailhouse.
>   
>   This is technically prohibited by the spec, so it is possible that
>   PCI devices without the Multi-Function Device bit set may have
>   unexpected behavior in response to this probe.
> 
>> The simple hypervisor Jailhouse passes subdevices directly w/o providing
>> a virtual PCI topology like KVM. As a consequence a PCI passthrough from
>> Jailhouse to a guest will not be detected by Linux.
>>
>> Based on patch by Benedikt Spranger, adding Jailhouse probing to avoid
>> changing the behavior in the absence of the hypervisor.
>>
>> CC: Benedikt Spranger 
>> Signed-off-by: Jan Kiszka 
> 
> With subject change to:
> 
>   PCI: Scan all functions when running over Jailhouse
> 
> Acked-by: Bjorn Helgaas 
> 

Thanks, all suggestions picked up for next round.

Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [PATCH 2/6] pci: Scan all functions when probing while running over Jailhouse

[Jan Kiszka]

On 2018-02-23 14:23, Andy Shevchenko wrote:
> On Mon, Jan 22, 2018 at 8:12 AM, Jan Kiszka  wrote:
> 
>>  #include 
>>  #include 
>>  #include 
>> +#include 
> 
> Keep it in order?
> 

Done.

> 
>>  #include 
>>  #include 
>>  #include 
>> +#include 
> 
> Ditto.
> 

Despite the context suggesting it, this file has no ordering.

Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [PATCH 2/6] pci: Scan all functions when probing while running over Jailhouse

[Andy Shevchenko]

On Mon, Jan 22, 2018 at 8:12 AM, Jan Kiszka  wrote:

>  #include 
>  #include 
>  #include 
> +#include 

Keep it in order?


>  #include 
>  #include 
>  #include 
> +#include 

Ditto.

-- 
With Best Regards,
Andy Shevchenko
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

[PATCH 2/6] pci: Scan all functions when probing while running over Jailhouse

[Jan Kiszka]

From: Jan Kiszka 

PCI and PCIBIOS probing only scans devices at function number 0/8/16/...
Subdevices (e.g. multiqueue) have function numbers which are not a
multiple of 8.

The simple hypervisor Jailhouse passes subdevices directly w/o providing
a virtual PCI topology like KVM. As a consequence a PCI passthrough from
Jailhouse to a guest will not be detected by Linux.

Based on patch by Benedikt Spranger, adding Jailhouse probing to avoid
changing the behavior in the absence of the hypervisor.

CC: Benedikt Spranger 
Signed-off-by: Jan Kiszka 
---
 arch/x86/pci/legacy.c | 4 +++-
 drivers/pci/probe.c   | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/pci/legacy.c b/arch/x86/pci/legacy.c
index 1cb01abcb1be..a7b0476b4f44 100644
--- a/arch/x86/pci/legacy.c
+++ b/arch/x86/pci/legacy.c
@@ -5,6 +5,7 @@
 #include 
 #include 
 #include 
+#include 
 
 /*
  * Discover remaining PCI buses in case there are peer host bridges.
@@ -34,13 +35,14 @@ int __init pci_legacy_init(void)
 
 void pcibios_scan_specific_bus(int busn)
 {
+   int stride = jailhouse_paravirt() ? 1 : 8;
int devfn;
u32 l;
 
if (pci_find_bus(0, busn))
return;
 
-   for (devfn = 0; devfn < 256; devfn += 8) {
+   for (devfn = 0; devfn < 256; devfn += stride) {
if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, ) &&
l != 0x && l != 0x) {
DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, 
l);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 14e0ea1ff38b..60ad14c8245f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -17,6 +17,7 @@
 #include 
 #include 
 #include 
+#include 
 #include "pci.h"
 
 #define CARDBUS_LATENCY_TIMER  176 /* secondary latency timer */
@@ -2454,6 +2455,7 @@ static unsigned int pci_scan_child_bus_extend(struct 
pci_bus *bus,
  unsigned int available_buses)
 {
unsigned int used_buses, normal_bridges = 0, hotplug_bridges = 0;
+   unsigned int stride = jailhouse_paravirt() ? 1 : 8;
unsigned int start = bus->busn_res.start;
unsigned int devfn, cmax, max = start;
struct pci_dev *dev;
@@ -2461,7 +2463,7 @@ static unsigned int pci_scan_child_bus_extend(struct 
pci_bus *bus,
dev_dbg(>dev, "scanning bus\n");
 
/* Go find them, Rover! */
-   for (devfn = 0; devfn < 0x100; devfn += 8)
+   for (devfn = 0; devfn < 0x100; devfn += stride)
pci_scan_slot(bus, devfn);
 
/* Reserve buses for SR-IOV capability. */
-- 
2.13.6

___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization