diff mbox series

[1/3] gpex-acpi: Support PCI link devices outside the host bridge

Message ID 20240528073103.1075812-2-sunilvl@ventanamicro.com (mailing list archive)
State New
Headers show
Series RISC-V: ACPI: Namespace updates | expand

Commit Message

Sunil V L May 28, 2024, 7:31 a.m. UTC
Currently, PCI link devices (PNP0C0F) are always created within the
scope of the PCI root complex. However, RISC-V needs PCI link devices to
be outside the scope of the PCI host bridge to properly enable the probe
order. This matches the example given in the ACPI specification section
6.2.13.1 as well.

Enable creating link devices outside the scope of PCI root complex based
on the flag which gets set currently only for RISC-V.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 hw/pci-host/gpex-acpi.c    | 29 ++++++++++++++++++++++++-----
 hw/riscv/virt-acpi-build.c |  8 +++++---
 include/hw/pci-host/gpex.h |  5 ++++-
 3 files changed, 33 insertions(+), 9 deletions(-)

Comments

Alistair Francis June 4, 2024, 11:06 p.m. UTC | #1
On Tue, May 28, 2024 at 5:32 PM Sunil V L <sunilvl@ventanamicro.com> wrote:
>
> Currently, PCI link devices (PNP0C0F) are always created within the
> scope of the PCI root complex. However, RISC-V needs PCI link devices to
> be outside the scope of the PCI host bridge to properly enable the probe
> order. This matches the example given in the ACPI specification section
> 6.2.13.1 as well.
>
> Enable creating link devices outside the scope of PCI root complex based
> on the flag which gets set currently only for RISC-V.
>
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>

Acked-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  hw/pci-host/gpex-acpi.c    | 29 ++++++++++++++++++++++++-----
>  hw/riscv/virt-acpi-build.c |  8 +++++---
>  include/hw/pci-host/gpex.h |  5 ++++-
>  3 files changed, 33 insertions(+), 9 deletions(-)
>
> diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
> index f69413ea2c..cea89a3ed8 100644
> --- a/hw/pci-host/gpex-acpi.c
> +++ b/hw/pci-host/gpex-acpi.c
> @@ -7,7 +7,7 @@
>  #include "hw/pci/pcie_host.h"
>  #include "hw/acpi/cxl.h"
>
> -static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
> +static void acpi_dsdt_add_pci_route_table(Aml *scope, Aml *dev, uint32_t irq)
>  {
>      Aml *method, *crs;
>      int i, slot_no;
> @@ -45,7 +45,17 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
>          aml_append(dev_gsi, aml_name_decl("_CRS", crs));
>          method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
>          aml_append(dev_gsi, method);
> -        aml_append(dev, dev_gsi);
> +
> +        /*
> +         * Some architectures like RISC-V need PCI link devices created
> +         * outside the scope of the PCI host bridge similar to the example
> +         * given in the section 6.2.13.1 of ACPI spec 6.5.
> +         */
> +         if (scope) {
> +            aml_append(scope, dev_gsi);
> +        } else {
> +            aml_append(dev, dev_gsi);
> +        }
>      }
>  }
>
> @@ -174,7 +184,11 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>                  aml_append(dev, aml_name_decl("_PXM", aml_int(numa_node)));
>              }
>
> -            acpi_dsdt_add_pci_route_table(dev, cfg->irq);
> +            if (cfg->flags & GPEX_FLAGS_EXT_GSI_LINK) {
> +                acpi_dsdt_add_pci_route_table(scope, dev, cfg->irq);
> +            } else {
> +                acpi_dsdt_add_pci_route_table(NULL, dev, cfg->irq);
> +            }
>
>              /*
>               * Resources defined for PXBs are composed of the following parts:
> @@ -205,7 +219,11 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>      aml_append(dev, aml_name_decl("_STR", aml_unicode("PCIe 0 Device")));
>      aml_append(dev, aml_name_decl("_CCA", aml_int(1)));
>
> -    acpi_dsdt_add_pci_route_table(dev, cfg->irq);
> +    if (cfg->flags & GPEX_FLAGS_EXT_GSI_LINK) {
> +        acpi_dsdt_add_pci_route_table(scope, dev, cfg->irq);
> +    } else {
> +        acpi_dsdt_add_pci_route_table(NULL, dev, cfg->irq);
> +    }
>
>      method = aml_method("_CBA", 0, AML_NOTSERIALIZED);
>      aml_append(method, aml_return(aml_int(cfg->ecam.base)));
> @@ -282,7 +300,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>      crs_range_set_free(&crs_range_set);
>  }
>
> -void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq)
> +void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq, uint32_t flags)
>  {
>      bool ambig;
>      Object *obj = object_resolve_path_type("", TYPE_GPEX_HOST, &ambig);
> @@ -292,5 +310,6 @@ void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq)
>      }
>
>      GPEX_HOST(obj)->gpex_cfg.irq = irq;
> +    GPEX_HOST(obj)->gpex_cfg.flags = flags;
>      acpi_dsdt_add_gpex(scope, &GPEX_HOST(obj)->gpex_cfg);
>  }
> diff --git a/hw/riscv/virt-acpi-build.c b/hw/riscv/virt-acpi-build.c
> index 0925528160..832a3acb8d 100644
> --- a/hw/riscv/virt-acpi-build.c
> +++ b/hw/riscv/virt-acpi-build.c
> @@ -417,19 +417,21 @@ static void build_dsdt(GArray *table_data,
>          virtio_acpi_dsdt_add(scope, memmap[VIRT_VIRTIO].base,
>                               memmap[VIRT_VIRTIO].size,
>                               VIRTIO_IRQ, 0, VIRTIO_COUNT);
> -        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ);
> +        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ, GPEX_FLAGS_EXT_GSI_LINK);
>      } else if (socket_count == 2) {
>          virtio_acpi_dsdt_add(scope, memmap[VIRT_VIRTIO].base,
>                               memmap[VIRT_VIRTIO].size,
>                               VIRTIO_IRQ + VIRT_IRQCHIP_NUM_SOURCES, 0,
>                               VIRTIO_COUNT);
> -        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES);
> +        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES,
> +                                GPEX_FLAGS_EXT_GSI_LINK);
>      } else {
>          virtio_acpi_dsdt_add(scope, memmap[VIRT_VIRTIO].base,
>                               memmap[VIRT_VIRTIO].size,
>                               VIRTIO_IRQ + VIRT_IRQCHIP_NUM_SOURCES, 0,
>                               VIRTIO_COUNT);
> -        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES * 2);
> +        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES * 2,
> +                                GPEX_FLAGS_EXT_GSI_LINK);
>      }
>
>      aml_append(dsdt, scope);
> diff --git a/include/hw/pci-host/gpex.h b/include/hw/pci-host/gpex.h
> index dce883573b..bee17d62c5 100644
> --- a/include/hw/pci-host/gpex.h
> +++ b/include/hw/pci-host/gpex.h
> @@ -47,8 +47,11 @@ struct GPEXConfig {
>      MemMapEntry pio;
>      int         irq;
>      PCIBus      *bus;
> +    uint32_t    flags;
>  };
>
> +#define GPEX_FLAGS_EXT_GSI_LINK BIT(0)
> +
>  struct GPEXHost {
>      /*< private >*/
>      PCIExpressHost parent_obj;
> @@ -71,7 +74,7 @@ struct GPEXHost {
>  int gpex_set_irq_num(GPEXHost *s, int index, int gsi);
>
>  void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg);
> -void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq);
> +void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq, uint32_t flags);
>
>  #define PCI_HOST_PIO_BASE               "x-pio-base"
>  #define PCI_HOST_PIO_SIZE               "x-pio-size"
> --
> 2.40.1
>
>
Michael S. Tsirkin June 5, 2024, 8:23 a.m. UTC | #2
On Tue, May 28, 2024 at 01:01:01PM +0530, Sunil V L wrote:
> Currently, PCI link devices (PNP0C0F) are always created within the
> scope of the PCI root complex. However, RISC-V needs PCI link devices to
> be outside the scope of the PCI host bridge to properly enable the probe
> order. This matches the example given in the ACPI specification section
> 6.2.13.1 as well.

Given that, what happens if we do this for all architectures?

> 
> Enable creating link devices outside the scope of PCI root complex based
> on the flag which gets set currently only for RISC-V.
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
>  hw/pci-host/gpex-acpi.c    | 29 ++++++++++++++++++++++++-----
>  hw/riscv/virt-acpi-build.c |  8 +++++---
>  include/hw/pci-host/gpex.h |  5 ++++-
>  3 files changed, 33 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
> index f69413ea2c..cea89a3ed8 100644
> --- a/hw/pci-host/gpex-acpi.c
> +++ b/hw/pci-host/gpex-acpi.c
> @@ -7,7 +7,7 @@
>  #include "hw/pci/pcie_host.h"
>  #include "hw/acpi/cxl.h"
>  
> -static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
> +static void acpi_dsdt_add_pci_route_table(Aml *scope, Aml *dev, uint32_t irq)
>  {
>      Aml *method, *crs;
>      int i, slot_no;
> @@ -45,7 +45,17 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
>          aml_append(dev_gsi, aml_name_decl("_CRS", crs));
>          method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
>          aml_append(dev_gsi, method);
> -        aml_append(dev, dev_gsi);
> +
> +        /*
> +         * Some architectures like RISC-V


Just risc-v for now right?
> need PCI link devices created
> +         * outside the scope of the PCI host bridge

.. in order to load the drivers in the correct order.
Others .... .

> similar to the example
> +         * given in the section 6.2.13.1 of ACPI spec 6.5.


This is not how we quote ACPI spec.

First you find the earliest spec version which has it.
Then you mention that, section/table # and title.
For example:

	ACPI 6.1: 18.3.2.8 Generic Hardware Error Source


> +         */
> +         if (scope) {
> +            aml_append(scope, dev_gsi);
> +        } else {
> +            aml_append(dev, dev_gsi);
> +        }
>      }
>  }
>  
> @@ -174,7 +184,11 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>                  aml_append(dev, aml_name_decl("_PXM", aml_int(numa_node)));
>              }
>  
> -            acpi_dsdt_add_pci_route_table(dev, cfg->irq);
> +            if (cfg->flags & GPEX_FLAGS_EXT_GSI_LINK) {
> +                acpi_dsdt_add_pci_route_table(scope, dev, cfg->irq);
> +            } else {
> +                acpi_dsdt_add_pci_route_table(NULL, dev, cfg->irq);
> +            }
>  
>              /*
>               * Resources defined for PXBs are composed of the following parts:
> @@ -205,7 +219,11 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>      aml_append(dev, aml_name_decl("_STR", aml_unicode("PCIe 0 Device")));
>      aml_append(dev, aml_name_decl("_CCA", aml_int(1)));
>  
> -    acpi_dsdt_add_pci_route_table(dev, cfg->irq);
> +    if (cfg->flags & GPEX_FLAGS_EXT_GSI_LINK) {
> +        acpi_dsdt_add_pci_route_table(scope, dev, cfg->irq);
> +    } else {
> +        acpi_dsdt_add_pci_route_table(NULL, dev, cfg->irq);
> +    }
>  
>      method = aml_method("_CBA", 0, AML_NOTSERIALIZED);
>      aml_append(method, aml_return(aml_int(cfg->ecam.base)));
> @@ -282,7 +300,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>      crs_range_set_free(&crs_range_set);
>  }
>  
> -void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq)
> +void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq, uint32_t flags)
>  {
>      bool ambig;
>      Object *obj = object_resolve_path_type("", TYPE_GPEX_HOST, &ambig);
> @@ -292,5 +310,6 @@ void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq)
>      }
>  
>      GPEX_HOST(obj)->gpex_cfg.irq = irq;
> +    GPEX_HOST(obj)->gpex_cfg.flags = flags;
>      acpi_dsdt_add_gpex(scope, &GPEX_HOST(obj)->gpex_cfg);
>  }
> diff --git a/hw/riscv/virt-acpi-build.c b/hw/riscv/virt-acpi-build.c
> index 0925528160..832a3acb8d 100644
> --- a/hw/riscv/virt-acpi-build.c
> +++ b/hw/riscv/virt-acpi-build.c
> @@ -417,19 +417,21 @@ static void build_dsdt(GArray *table_data,
>          virtio_acpi_dsdt_add(scope, memmap[VIRT_VIRTIO].base,
>                               memmap[VIRT_VIRTIO].size,
>                               VIRTIO_IRQ, 0, VIRTIO_COUNT);
> -        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ);
> +        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ, GPEX_FLAGS_EXT_GSI_LINK);
>      } else if (socket_count == 2) {
>          virtio_acpi_dsdt_add(scope, memmap[VIRT_VIRTIO].base,
>                               memmap[VIRT_VIRTIO].size,
>                               VIRTIO_IRQ + VIRT_IRQCHIP_NUM_SOURCES, 0,
>                               VIRTIO_COUNT);
> -        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES);
> +        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES,
> +                                GPEX_FLAGS_EXT_GSI_LINK);
>      } else {
>          virtio_acpi_dsdt_add(scope, memmap[VIRT_VIRTIO].base,
>                               memmap[VIRT_VIRTIO].size,
>                               VIRTIO_IRQ + VIRT_IRQCHIP_NUM_SOURCES, 0,
>                               VIRTIO_COUNT);
> -        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES * 2);
> +        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES * 2,
> +                                GPEX_FLAGS_EXT_GSI_LINK);
>      }
>  
>      aml_append(dsdt, scope);
> diff --git a/include/hw/pci-host/gpex.h b/include/hw/pci-host/gpex.h
> index dce883573b..bee17d62c5 100644
> --- a/include/hw/pci-host/gpex.h
> +++ b/include/hw/pci-host/gpex.h
> @@ -47,8 +47,11 @@ struct GPEXConfig {
>      MemMapEntry pio;
>      int         irq;
>      PCIBus      *bus;
> +    uint32_t    flags;
>  };
>  
> +#define GPEX_FLAGS_EXT_GSI_LINK BIT(0)
> +
>  struct GPEXHost {
>      /*< private >*/
>      PCIExpressHost parent_obj;
> @@ -71,7 +74,7 @@ struct GPEXHost {
>  int gpex_set_irq_num(GPEXHost *s, int index, int gsi);
>  
>  void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg);
> -void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq);
> +void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq, uint32_t flags);
>  
>  #define PCI_HOST_PIO_BASE               "x-pio-base"
>  #define PCI_HOST_PIO_SIZE               "x-pio-size"
> -- 
> 2.40.1
> 
>
Sunil V L June 5, 2024, 11:43 a.m. UTC | #3
Hi Michael,

Thank you very much for the review!

On Wed, Jun 05, 2024 at 04:23:36AM -0400, Michael S. Tsirkin wrote:
> On Tue, May 28, 2024 at 01:01:01PM +0530, Sunil V L wrote:
> > Currently, PCI link devices (PNP0C0F) are always created within the
> > scope of the PCI root complex. However, RISC-V needs PCI link devices to
> > be outside the scope of the PCI host bridge to properly enable the probe
> > order. This matches the example given in the ACPI specification section
> > 6.2.13.1 as well.
> 
> Given that, what happens if we do this for all architectures?
> 
In theory and from my observation of linux on arm64, this should not
have any impact. However, I was bit hesitant to change for other
architectures since I was not sure how namespace changes like this will
affect different OS/architecture combination.

It looks like there is no real concern to make this change generic. That
should simplify the patch as well. Let me update in next version.
It would also warrant updating ACPI table blob for bios-table-test.

> > 
> > Enable creating link devices outside the scope of PCI root complex based
> > on the flag which gets set currently only for RISC-V.
> > 
> > Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> > ---
> >  hw/pci-host/gpex-acpi.c    | 29 ++++++++++++++++++++++++-----
> >  hw/riscv/virt-acpi-build.c |  8 +++++---
> >  include/hw/pci-host/gpex.h |  5 ++++-
> >  3 files changed, 33 insertions(+), 9 deletions(-)
> > 
> > diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
> > index f69413ea2c..cea89a3ed8 100644
> > --- a/hw/pci-host/gpex-acpi.c
> > +++ b/hw/pci-host/gpex-acpi.c
> > @@ -7,7 +7,7 @@
> >  #include "hw/pci/pcie_host.h"
> >  #include "hw/acpi/cxl.h"
> >  
> > -static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
> > +static void acpi_dsdt_add_pci_route_table(Aml *scope, Aml *dev, uint32_t irq)
> >  {
> >      Aml *method, *crs;
> >      int i, slot_no;
> > @@ -45,7 +45,17 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
> >          aml_append(dev_gsi, aml_name_decl("_CRS", crs));
> >          method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
> >          aml_append(dev_gsi, method);
> > -        aml_append(dev, dev_gsi);
> > +
> > +        /*
> > +         * Some architectures like RISC-V
> 
> 
> Just risc-v for now right?
> > need PCI link devices created
> > +         * outside the scope of the PCI host bridge
> 
> .. in order to load the drivers in the correct order.
> Others .... .
> 
Okay.

> > similar to the example
> > +         * given in the section 6.2.13.1 of ACPI spec 6.5.
> 
> 
> This is not how we quote ACPI spec.
> 
> First you find the earliest spec version which has it.
> Then you mention that, section/table # and title.
> For example:
> 
> 	ACPI 6.1: 18.3.2.8 Generic Hardware Error Source
> 
>
Thanks!. Let me update as you suggested.

Thanks,
Sunil
diff mbox series

Patch

diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
index f69413ea2c..cea89a3ed8 100644
--- a/hw/pci-host/gpex-acpi.c
+++ b/hw/pci-host/gpex-acpi.c
@@ -7,7 +7,7 @@ 
 #include "hw/pci/pcie_host.h"
 #include "hw/acpi/cxl.h"
 
-static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
+static void acpi_dsdt_add_pci_route_table(Aml *scope, Aml *dev, uint32_t irq)
 {
     Aml *method, *crs;
     int i, slot_no;
@@ -45,7 +45,17 @@  static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
         aml_append(dev_gsi, aml_name_decl("_CRS", crs));
         method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
         aml_append(dev_gsi, method);
-        aml_append(dev, dev_gsi);
+
+        /*
+         * Some architectures like RISC-V need PCI link devices created
+         * outside the scope of the PCI host bridge similar to the example
+         * given in the section 6.2.13.1 of ACPI spec 6.5.
+         */
+         if (scope) {
+            aml_append(scope, dev_gsi);
+        } else {
+            aml_append(dev, dev_gsi);
+        }
     }
 }
 
@@ -174,7 +184,11 @@  void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
                 aml_append(dev, aml_name_decl("_PXM", aml_int(numa_node)));
             }
 
-            acpi_dsdt_add_pci_route_table(dev, cfg->irq);
+            if (cfg->flags & GPEX_FLAGS_EXT_GSI_LINK) {
+                acpi_dsdt_add_pci_route_table(scope, dev, cfg->irq);
+            } else {
+                acpi_dsdt_add_pci_route_table(NULL, dev, cfg->irq);
+            }
 
             /*
              * Resources defined for PXBs are composed of the following parts:
@@ -205,7 +219,11 @@  void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
     aml_append(dev, aml_name_decl("_STR", aml_unicode("PCIe 0 Device")));
     aml_append(dev, aml_name_decl("_CCA", aml_int(1)));
 
-    acpi_dsdt_add_pci_route_table(dev, cfg->irq);
+    if (cfg->flags & GPEX_FLAGS_EXT_GSI_LINK) {
+        acpi_dsdt_add_pci_route_table(scope, dev, cfg->irq);
+    } else {
+        acpi_dsdt_add_pci_route_table(NULL, dev, cfg->irq);
+    }
 
     method = aml_method("_CBA", 0, AML_NOTSERIALIZED);
     aml_append(method, aml_return(aml_int(cfg->ecam.base)));
@@ -282,7 +300,7 @@  void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
     crs_range_set_free(&crs_range_set);
 }
 
-void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq)
+void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq, uint32_t flags)
 {
     bool ambig;
     Object *obj = object_resolve_path_type("", TYPE_GPEX_HOST, &ambig);
@@ -292,5 +310,6 @@  void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq)
     }
 
     GPEX_HOST(obj)->gpex_cfg.irq = irq;
+    GPEX_HOST(obj)->gpex_cfg.flags = flags;
     acpi_dsdt_add_gpex(scope, &GPEX_HOST(obj)->gpex_cfg);
 }
diff --git a/hw/riscv/virt-acpi-build.c b/hw/riscv/virt-acpi-build.c
index 0925528160..832a3acb8d 100644
--- a/hw/riscv/virt-acpi-build.c
+++ b/hw/riscv/virt-acpi-build.c
@@ -417,19 +417,21 @@  static void build_dsdt(GArray *table_data,
         virtio_acpi_dsdt_add(scope, memmap[VIRT_VIRTIO].base,
                              memmap[VIRT_VIRTIO].size,
                              VIRTIO_IRQ, 0, VIRTIO_COUNT);
-        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ);
+        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ, GPEX_FLAGS_EXT_GSI_LINK);
     } else if (socket_count == 2) {
         virtio_acpi_dsdt_add(scope, memmap[VIRT_VIRTIO].base,
                              memmap[VIRT_VIRTIO].size,
                              VIRTIO_IRQ + VIRT_IRQCHIP_NUM_SOURCES, 0,
                              VIRTIO_COUNT);
-        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES);
+        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES,
+                                GPEX_FLAGS_EXT_GSI_LINK);
     } else {
         virtio_acpi_dsdt_add(scope, memmap[VIRT_VIRTIO].base,
                              memmap[VIRT_VIRTIO].size,
                              VIRTIO_IRQ + VIRT_IRQCHIP_NUM_SOURCES, 0,
                              VIRTIO_COUNT);
-        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES * 2);
+        acpi_dsdt_add_gpex_host(scope, PCIE_IRQ + VIRT_IRQCHIP_NUM_SOURCES * 2,
+                                GPEX_FLAGS_EXT_GSI_LINK);
     }
 
     aml_append(dsdt, scope);
diff --git a/include/hw/pci-host/gpex.h b/include/hw/pci-host/gpex.h
index dce883573b..bee17d62c5 100644
--- a/include/hw/pci-host/gpex.h
+++ b/include/hw/pci-host/gpex.h
@@ -47,8 +47,11 @@  struct GPEXConfig {
     MemMapEntry pio;
     int         irq;
     PCIBus      *bus;
+    uint32_t    flags;
 };
 
+#define GPEX_FLAGS_EXT_GSI_LINK BIT(0)
+
 struct GPEXHost {
     /*< private >*/
     PCIExpressHost parent_obj;
@@ -71,7 +74,7 @@  struct GPEXHost {
 int gpex_set_irq_num(GPEXHost *s, int index, int gsi);
 
 void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg);
-void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq);
+void acpi_dsdt_add_gpex_host(Aml *scope, uint32_t irq, uint32_t flags);
 
 #define PCI_HOST_PIO_BASE               "x-pio-base"
 #define PCI_HOST_PIO_SIZE               "x-pio-size"