Re: [kvm-unit-tests PATCH v2 05/23] arm/arm64: Add support for setting up the PSCI conduit through ACPI

[Ricardo Koller <ricarkol@google.com>]

On Fri, May 06, 2022 at 09:55:47PM +0100, Nikos Nikoleris wrote:
> In systems with ACPI support and when a DT is not provided, we can use
> the FADT to discover whether PSCI calls need to use smc or hvc
> calls. This change implements this but retains the default behavior;
> we check if a valid DT is provided, if not, we try to setup the PSCI
> conduit using ACPI.
> 
> Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
> ---
>  arm/Makefile.common |  1 +
>  lib/acpi.h          |  5 +++++
>  lib/arm/psci.c      | 23 ++++++++++++++++++++++-
>  lib/devicetree.c    |  2 +-
>  4 files changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/arm/Makefile.common b/arm/Makefile.common
> index 38385e0..8e9b3bb 100644
> --- a/arm/Makefile.common
> +++ b/arm/Makefile.common
> @@ -38,6 +38,7 @@ cflatobjs += lib/alloc_page.o
>  cflatobjs += lib/vmalloc.o
>  cflatobjs += lib/alloc.o
>  cflatobjs += lib/devicetree.o
> +cflatobjs += lib/acpi.o
>  cflatobjs += lib/pci.o
>  cflatobjs += lib/pci-host-generic.o
>  cflatobjs += lib/pci-testdev.o
> diff --git a/lib/acpi.h b/lib/acpi.h
> index 9f27eb1..139ccba 100644
> --- a/lib/acpi.h
> +++ b/lib/acpi.h
> @@ -130,6 +130,11 @@ struct acpi_table_fadt
>      u64 hypervisor_id;      /* Hypervisor Vendor ID (ACPI 6.0) */
>  }  __attribute__ ((packed));
>  
> +/* Masks for FADT ARM Boot Architecture Flags (arm_boot_flags) ACPI 5.1 */
> +
> +#define ACPI_FADT_PSCI_COMPLIANT    (1)         /* 00: [V5+] PSCI 0.2+ is implemented */
> +#define ACPI_FADT_PSCI_USE_HVC      (1<<1)      /* 01: [V5+] HVC must be used instead of SMC as the PSCI conduit */
> +
>  struct facs_descriptor_rev1
>  {
>      u32 signature;           /* ACPI Signature */
> diff --git a/lib/arm/psci.c b/lib/arm/psci.c
> index 9c031a1..0e96d19 100644
> --- a/lib/arm/psci.c
> +++ b/lib/arm/psci.c
> @@ -6,6 +6,7 @@
>   *
>   * This work is licensed under the terms of the GNU LGPL, version 2.
>   */
> +#include <acpi.h>
>  #include <devicetree.h>
>  #include <asm/psci.h>
>  #include <asm/setup.h>
> @@ -56,7 +57,7 @@ void psci_system_off(void)
>  	printf("CPU%d unable to do system off (error = %d)\n", smp_processor_id(), err);
>  }
>  
> -void psci_set_conduit(void)
> +static void psci_set_conduit_fdt(void)
>  {
>  	const void *fdt = dt_fdt();
>  	const struct fdt_property *method;
> @@ -75,3 +76,23 @@ void psci_set_conduit(void)
>  	else
>  		assert_msg(false, "Unknown PSCI conduit: %s", method->data);
>  }
> +
> +static void psci_set_conduit_acpi(void)
> +{
> +	struct acpi_table_fadt *fadt = find_acpi_table_addr(FACP_SIGNATURE);
> +	assert_msg(fadt, "Unable to find ACPI FADT");
> +	assert_msg(fadt->arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT,
> +		   "PSCI is not supported in this platfrom");
> +	if (fadt->arm_boot_flags & ACPI_FADT_PSCI_USE_HVC)
> +		psci_invoke = psci_invoke_hvc;
> +	else
> +		psci_invoke = psci_invoke_smc;
> +}
> +
> +void psci_set_conduit(void)
> +{
> +	if (dt_available())
> +		psci_set_conduit_fdt();
> +	else
> +		psci_set_conduit_acpi();
> +}
> diff --git a/lib/devicetree.c b/lib/devicetree.c
> index 78c1f6f..3ff9d16 100644
> --- a/lib/devicetree.c
> +++ b/lib/devicetree.c
> @@ -16,7 +16,7 @@ const void *dt_fdt(void)
>  
>  bool dt_available(void)
>  {
> -	return fdt_check_header(fdt) == 0;
> +	return fdt && fdt_check_header(fdt) == 0;
>  }
>  
>  int dt_get_nr_cells(int fdtnode, u32 *nr_address_cells, u32 *nr_size_cells)
> -- 
>2.25.1
>

Reviewed-by: Ricardo Koller <ricarkol@google.com>