Re: [RFC KERNEL PATCH v4 2/3] xen/pvh: Setup gsi for passthrough device

["Chen, Jiqian" <Jiqian.Chen@xxxxxxx>]

On 2024/2/23 08:23, Stefano Stabellini wrote:
> On Fri, 5 Jan 2024, Jiqian Chen wrote:
>> In PVH dom0, the gsis don't get registered, but the gsi of
>> a passthrough device must be configured for it to be able to be
>> mapped into a domU.
>>
>> When assign a device to passthrough, proactively setup the gsi
>> of the device during that process.
>>
>> Co-developed-by: Huang Rui <ray.huang@xxxxxxx>
>> Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
>> ---
>>  arch/x86/xen/enlighten_pvh.c       | 90 ++++++++++++++++++++++++++++++
>>  drivers/acpi/pci_irq.c             |  2 +-
>>  drivers/xen/xen-pciback/pci_stub.c |  8 +++
>>  include/linux/acpi.h               |  1 +
>>  include/xen/acpi.h                 |  6 ++
>>  5 files changed, 106 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
>> index ada3868c02c2..ecadd966c684 100644
>> --- a/arch/x86/xen/enlighten_pvh.c
>> +++ b/arch/x86/xen/enlighten_pvh.c
>> @@ -1,6 +1,7 @@
>>  // SPDX-License-Identifier: GPL-2.0
>>  #include <linux/acpi.h>
>>  #include <linux/export.h>
>> +#include <linux/pci.h>
>>  
>>  #include <xen/hvc-console.h>
>>  
>> @@ -25,6 +26,95 @@
>>  bool __ro_after_init xen_pvh;
>>  EXPORT_SYMBOL_GPL(xen_pvh);
>>  
>> +typedef struct gsi_info {
>> +    int gsi;
>> +    int trigger;
>> +    int polarity;
>> +} gsi_info_t;
>> +
>> +struct acpi_prt_entry {
>> +    struct acpi_pci_id      id;
>> +    u8                      pin;
>> +    acpi_handle             link;
>> +    u32                     index;          /* GSI, or link _CRS index */
>> +};
>> +
>> +static int xen_pvh_get_gsi_info(struct pci_dev *dev,
>> +                                                            gsi_info_t 
>> *gsi_info)
>> +{
>> +    int gsi;
>> +    u8 pin = 0;
>> +    struct acpi_prt_entry *entry;
>> +    int trigger = ACPI_LEVEL_SENSITIVE;
>> +    int polarity = acpi_irq_model == ACPI_IRQ_MODEL_GIC ?
>> +                                  ACPI_ACTIVE_HIGH : ACPI_ACTIVE_LOW;
>> +
>> +    if (dev)
>> +            pin = dev->pin;
> 
> This is minor, but you can just move the pin = dev->pin after the !dev
> check below.
Will change in next version.

> 
> With that change, and assuming the Xen-side and QEMU-side patches are
> accepted:
> 
> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Thank you very much!

> 
> 
> 
> 
>> +    if (!dev || !pin || !gsi_info)
>> +            return -EINVAL;
>> +
>> +    entry = acpi_pci_irq_lookup(dev, pin);
>> +    if (entry) {
>> +            if (entry->link)
>> +                    gsi = acpi_pci_link_allocate_irq(entry->link,
>> +                                                     entry->index,
>> +                                                     &trigger, &polarity,
>> +                                                     NULL);
>> +            else
>> +                    gsi = entry->index;
>> +    } else
>> +            gsi = -1;
>> +
>> +    if (gsi < 0)
>> +            return -EINVAL;
>> +
>> +    gsi_info->gsi = gsi;
>> +    gsi_info->trigger = trigger;
>> +    gsi_info->polarity = polarity;
>> +
>> +    return 0;
>> +}
>> +
>> +static int xen_pvh_setup_gsi(gsi_info_t *gsi_info)
>> +{
>> +    struct physdev_setup_gsi setup_gsi;
>> +
>> +    if (!gsi_info)
>> +            return -EINVAL;
>> +
>> +    setup_gsi.gsi = gsi_info->gsi;
>> +    setup_gsi.triggering = (gsi_info->trigger == ACPI_EDGE_SENSITIVE ? 0 : 
>> 1);
>> +    setup_gsi.polarity = (gsi_info->polarity == ACPI_ACTIVE_HIGH ? 0 : 1);
>> +
>> +    return HYPERVISOR_physdev_op(PHYSDEVOP_setup_gsi, &setup_gsi);
>> +}
>> +
>> +int xen_pvh_passthrough_gsi(struct pci_dev *dev)
>> +{
>> +    int ret;
>> +    gsi_info_t gsi_info;
>> +
>> +    if (!dev)
>> +            return -EINVAL;
>> +
>> +    ret = xen_pvh_get_gsi_info(dev, &gsi_info);
>> +    if (ret) {
>> +            xen_raw_printk("Fail to get gsi info!\n");
>> +            return ret;
>> +    }
>> +
>> +    ret = xen_pvh_setup_gsi(&gsi_info);
>> +    if (ret == -EEXIST) {
>> +            xen_raw_printk("Already setup the GSI :%d\n", gsi_info.gsi);
>> +            ret = 0;
>> +    } else if (ret)
>> +            xen_raw_printk("Fail to setup GSI (%d)!\n", gsi_info.gsi);
>> +
>> +    return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(xen_pvh_passthrough_gsi);
>> +
>>  void __init xen_pvh_init(struct boot_params *boot_params)
>>  {
>>      u32 msr;
>> diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
>> index ff30ceca2203..630fe0a34bc6 100644
>> --- a/drivers/acpi/pci_irq.c
>> +++ b/drivers/acpi/pci_irq.c
>> @@ -288,7 +288,7 @@ static int acpi_reroute_boot_interrupt(struct pci_dev 
>> *dev,
>>  }
>>  #endif /* CONFIG_X86_IO_APIC */
>>  
>> -static struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int 
>> pin)
>> +struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin)
>>  {
>>      struct acpi_prt_entry *entry = NULL;
>>      struct pci_dev *bridge;
>> diff --git a/drivers/xen/xen-pciback/pci_stub.c 
>> b/drivers/xen/xen-pciback/pci_stub.c
>> index 46c40ec8a18e..22d4380d2b04 100644
>> --- a/drivers/xen/xen-pciback/pci_stub.c
>> +++ b/drivers/xen/xen-pciback/pci_stub.c
>> @@ -20,6 +20,7 @@
>>  #include <linux/atomic.h>
>>  #include <xen/events.h>
>>  #include <xen/pci.h>
>> +#include <xen/acpi.h>
>>  #include <xen/xen.h>
>>  #include <asm/xen/hypervisor.h>
>>  #include <xen/interface/physdev.h>
>> @@ -435,6 +436,13 @@ static int pcistub_init_device(struct pci_dev *dev)
>>                      goto config_release;
>>              pci_restore_state(dev);
>>      }
>> +
>> +    if (xen_initial_domain() && xen_pvh_domain()) {
>> +            err = xen_pvh_passthrough_gsi(dev);
>> +            if (err)
>> +                    goto config_release;
>> +    }
>> +
>>      /* Now disable the device (this also ensures some private device
>>       * data is setup before we export)
>>       */
>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> index 4db54e928b36..7ea3be981cc3 100644
>> --- a/include/linux/acpi.h
>> +++ b/include/linux/acpi.h
>> @@ -360,6 +360,7 @@ void acpi_unregister_gsi (u32 gsi);
>>  
>>  struct pci_dev;
>>  
>> +struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin);
>>  int acpi_pci_irq_enable (struct pci_dev *dev);
>>  void acpi_penalize_isa_irq(int irq, int active);
>>  bool acpi_isa_irq_available(int irq);
>> diff --git a/include/xen/acpi.h b/include/xen/acpi.h
>> index b1e11863144d..17c4d37f1e60 100644
>> --- a/include/xen/acpi.h
>> +++ b/include/xen/acpi.h
>> @@ -67,10 +67,16 @@ static inline void xen_acpi_sleep_register(void)
>>              acpi_suspend_lowlevel = xen_acpi_suspend_lowlevel;
>>      }
>>  }
>> +int xen_pvh_passthrough_gsi(struct pci_dev *dev);
>>  #else
>>  static inline void xen_acpi_sleep_register(void)
>>  {
>>  }
>> +
>> +static inline int xen_pvh_passthrough_gsi(struct pci_dev *dev)
>> +{
>> +    return -1;
>> +}
>>  #endif
>>  
>>  #endif      /* _XEN_ACPI_H */
>> -- 
>> 2.34.1
>>

-- 
Best regards,
Jiqian Chen.