Re: [PATCH v1 23/23] s3 support: enabling s3 with q35

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 20 Jun 2023 13:24:57 -0400
Joel Upham <jupham125@gmail.com> wrote:

> Resetting pci devices after s3 causes guest freezes, as xen usually
> likes to handle resetting devices.

I'd prefer Xen side being fixed instead of hacking reset logic in qemu/q35.
 

> Signed-off-by: Joel Upham <jupham125@gmail.com>
> ---
>  hw/acpi/ich9.c    | 12 ++++++++----
>  hw/pci-host/q35.c |  3 ++-
>  2 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
> index 1c236be1c7..234706a191 100644
> --- a/hw/acpi/ich9.c
> +++ b/hw/acpi/ich9.c
> @@ -143,7 +143,8 @@ static int ich9_pm_post_load(void *opaque, int version_id)
>  {
>      ICH9LPCPMRegs *pm = opaque;
>      uint32_t pm_io_base = pm->pm_io_base;
> -    pm->pm_io_base = 0;
> +    if (!xen_enabled())
> +        pm->pm_io_base = 0;
>      ich9_pm_iospace_update(pm, pm_io_base);
>      return 0;
>  }
> @@ -274,7 +275,10 @@ static void pm_reset(void *opaque)
>      acpi_pm1_evt_reset(&pm->acpi_regs);
>      acpi_pm1_cnt_reset(&pm->acpi_regs);
>      acpi_pm_tmr_reset(&pm->acpi_regs);
> -    acpi_gpe_reset(&pm->acpi_regs);
> +    /* Noticed guest freezing in xen when this was reset after S3. */
> +    if (!xen_enabled()) {
> +        acpi_gpe_reset(&pm->acpi_regs);
> +    }
>  
>      pm->smi_en = 0;
>      if (!pm->smm_enabled) {
> @@ -322,7 +326,7 @@ void ich9_pm_init(PCIDevice *lpc_pci, ICH9LPCPMRegs *pm, qemu_irq sci_irq)
>          acpi_pm_tco_init(&pm->tco_regs, &pm->io);
>      }
>  
> -    if (pm->acpi_pci_hotplug.use_acpi_hotplug_bridge) {
> +    if (pm->acpi_pci_hotplug.use_acpi_hotplug_bridge || xen_enabled()) {
>          acpi_pcihp_init(OBJECT(lpc_pci),
>                          &pm->acpi_pci_hotplug,
>                          pci_get_bus(lpc_pci),
> @@ -345,7 +349,7 @@ void ich9_pm_init(PCIDevice *lpc_pci, ICH9LPCPMRegs *pm, qemu_irq sci_irq)
>      legacy_acpi_cpu_hotplug_init(pci_address_space_io(lpc_pci),
>          OBJECT(lpc_pci), &pm->gpe_cpu, ICH9_CPU_HOTPLUG_IO_BASE);
>  
> -    if (pm->acpi_memory_hotplug.is_enabled) {
> +    if (pm->acpi_memory_hotplug.is_enabled || xen_enabled()) {
>          acpi_memory_hotplug_init(pci_address_space_io(lpc_pci), OBJECT(lpc_pci),
>                                   &pm->acpi_memory_hotplug,
>                                   ACPI_MEMORY_HOTPLUG_BASE);
> diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> index 1fe4e5a5c9..5891839ce9 100644
> --- a/hw/pci-host/q35.c
> +++ b/hw/pci-host/q35.c
> @@ -580,7 +580,8 @@ static void mch_reset(DeviceState *qdev)
>      d->config[MCH_HOST_BRIDGE_F_SMBASE] = 0;
>      d->wmask[MCH_HOST_BRIDGE_F_SMBASE] = 0xff;
>  
> -    mch_update(mch);
> +    if (!xen_enabled())
> +        mch_update(mch);
>  }
>  
>  static void mch_realize(PCIDevice *d, Error **errp)