Re: [PATCH v4 08/11] libxl: Only map legacy PCI IRQs if they are supported

[Rahul Singh <Rahul.Singh@arm.com>]

Hi Oleksandr,

> On 4 Oct 2021, at 3:11 pm, Oleksandr Andrushchenko <andr2000@gmail.com> wrote:
> 
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> 
> Arm's PCI passthrough implementation doesn't support legacy interrupts,
> but MSI/MSI-X. This can be the case for other platforms too.
> For that reason introduce a new CONFIG_PCI_SUPP_LEGACY_IRQ and add
> it to the CFLAGS and compile the relevant code in the toolstack only if
> applicable.
> 
> Cc: Ian Jackson <iwj@xenproject.org>
> Cc: Juergen Gross <jgross@suse.com>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

Reviewed-by: Rahul Singh <rahul.singh@arm.com>
Tested-by: Rahul Singh <rahul.singh@arm.com>

Regards,
Rahul
> ---
> Since v1:
> - Minimized #idefery by introducing pci_supp_legacy_irq function
>   for relevant checks
> ---
> tools/libs/light/Makefile    |  4 ++++
> tools/libs/light/libxl_pci.c | 13 +++++++++++++
> 2 files changed, 17 insertions(+)
> 
> diff --git a/tools/libs/light/Makefile b/tools/libs/light/Makefile
> index 7d8c51d49242..bd3f6be2a183 100644
> --- a/tools/libs/light/Makefile
> +++ b/tools/libs/light/Makefile
> @@ -46,6 +46,10 @@ CFLAGS += -Wno-format-zero-length -Wmissing-declarations \
> 	-Wno-declaration-after-statement -Wformat-nonliteral
> CFLAGS += -I.
> 
> +ifeq ($(CONFIG_X86),y)
> +CFLAGS += -DCONFIG_PCI_SUPP_LEGACY_IRQ
> +endif
> +
> SRCS-$(CONFIG_X86) += libxl_cpuid.c
> SRCS-$(CONFIG_X86) += libxl_x86.c
> SRCS-$(CONFIG_X86) += libxl_psr.c
> diff --git a/tools/libs/light/libxl_pci.c b/tools/libs/light/libxl_pci.c
> index 59f3686fc85e..4c2d7aeefbb2 100644
> --- a/tools/libs/light/libxl_pci.c
> +++ b/tools/libs/light/libxl_pci.c
> @@ -1364,6 +1364,15 @@ static void pci_add_timeout(libxl__egc *egc, libxl__ev_time *ev,
>     pci_add_dm_done(egc, pas, rc);
> }
> 
> +static bool pci_supp_legacy_irq(void)
> +{
> +#ifdef CONFIG_PCI_SUPP_LEGACY_IRQ
> +    return true;
> +#else
> +    return false;
> +#endif
> +}
> +
> static void pci_add_dm_done(libxl__egc *egc,
>                             pci_add_state *pas,
>                             int rc)
> @@ -1434,6 +1443,8 @@ static void pci_add_dm_done(libxl__egc *egc,
>         }
>     }
>     fclose(f);
> +    if (!pci_supp_legacy_irq())
> +        goto out_no_irq;
>     sysfs_path = GCSPRINTF(SYSFS_PCI_DEV"/"PCI_BDF"/irq", pci->domain,
>                                 pci->bus, pci->dev, pci->func);
>     f = fopen(sysfs_path, "r");
> @@ -1983,6 +1994,8 @@ static void do_pci_remove(libxl__egc *egc, pci_remove_state *prs)
>         }
>         fclose(f);
> skip1:
> +        if (!pci_supp_legacy_irq())
> +            goto skip_irq;
>         sysfs_path = GCSPRINTF(SYSFS_PCI_DEV"/"PCI_BDF"/irq", pci->domain,
>                                pci->bus, pci->dev, pci->func);
>         f = fopen(sysfs_path, "r");
> -- 
> 2.25.1
>