On Mon, 26 Jul 2021 22:27:43 +0530
Ani Sinha <a...@anisinha.ca> wrote:
> All existing code using acpi_get_i386_pci_host() checks for a non-null
> return value from this function call. Instead of returning early when the
> value
> returned is NULL, assert instead. Since there are only two possible host buses
> for i386 - q35 and i440fx, a null value return from the function does not make
> sense in most cases and is likely an error situation.
>
> Fixes: c0e427d6eb5fef ("hw/acpi/ich9: Enable ACPI PCI hot-plug")
>
> Signed-off-by: Ani Sinha <a...@anisinha.ca>
> ---
> hw/acpi/pcihp.c | 8 ++++++++
> hw/i386/acpi-build.c | 15 ++++++---------
> 2 files changed, 14 insertions(+), 9 deletions(-)
>
> changelog:
> v1: initial patch
> v2: removed comment addition - that can be sent as a separate patch.
> v3: added assertion for null host values for all cases except one.
>
> diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
> index f4d706e47d..054ee8cbc5 100644
> --- a/hw/acpi/pcihp.c
> +++ b/hw/acpi/pcihp.c
> @@ -116,6 +116,12 @@ static void acpi_set_pci_info(void)
> bsel_is_set = true;
>
> if (!host) {
> + /*
> + * This function can be eventually called from
> + * qemu_devices_reset() -> acpi_pcihp_reset() even
> + * for architectures other than i386. Hence, we need
> + * to ignore null values for host here.
> + */
> return;
> }
I suspect it's a MIPS target that call this code unnecessarily.
It would be better to get rid of this condition altogether.
Frr that I can suggest to make acpi_pcihp_reset() stub and
replace pcihp.c with stub (perhaps use acpi-x86-stub.c) when building
for MIPS.
then a bunch of asserts/ifs won't be necessary,
just one in acpi_get_i386_pci_host() will be sufficient.
> @@ -136,6 +142,8 @@ static void acpi_pcihp_disable_root_bus(void)
> return;
> }
>
> + assert(host);
> +
> bus = PCI_HOST_BRIDGE(host)->bus;
> if (bus) {
> /* setting the hotplug handler to NULL makes the bus
> non-hotpluggable */
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 17836149fe..83fb1d55c0 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -321,9 +321,7 @@ static void acpi_get_pci_holes(Range *hole, Range *hole64)
>
> pci_host = acpi_get_i386_pci_host();
>
> - if (!pci_host) {
> - return;
> - }
> + assert(pci_host);
>
> range_set_bounds1(hole,
> object_property_get_uint(pci_host,
> @@ -1769,9 +1767,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
>
> pci_host = acpi_get_i386_pci_host();
>
> - if (pci_host) {
> - bus = PCI_HOST_BRIDGE(pci_host)->bus;
> - }
> + assert(pci_host);
> +
> + bus = PCI_HOST_BRIDGE(pci_host)->bus;
>
> if (bus) {
> Aml *scope = aml_scope("PCI0");
> @@ -2389,9 +2387,8 @@ static bool acpi_get_mcfg(AcpiMcfgInfo *mcfg)
> QObject *o;
>
> pci_host = acpi_get_i386_pci_host();
> - if (!pci_host) {
> - return false;
> - }
> +
> + assert(pci_host);
>
> o = object_property_get_qobject(pci_host, PCIE_HOST_MCFG_BASE, NULL);
> if (!o) {
