Re: [kvm-unit-tests PATCH v5 08/29] lib/acpi: Add support for the XSDT table

[Shaoqin Huang <shahuang@redhat.com>]

On 4/28/23 20:03, Nikos Nikoleris wrote:
> XSDT provides pointers to other ACPI tables much like RSDT. However,
> contrary to RSDT that provides 32-bit addresses, XSDT provides 64-bit
> pointers. ACPI requires that if XSDT is valid then it takes precedence
> over RSDT.
> 
> Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
> Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
> [ Alex E: Use flexible array member for XSDT struct ]
> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
> ---
>   lib/acpi.h |  6 ++++++
>   lib/acpi.c | 40 ++++++++++++++++++++++++++++++++--------
>   2 files changed, 38 insertions(+), 8 deletions(-)
> 
> diff --git a/lib/acpi.h b/lib/acpi.h
> index 53e41c4b..74ba00ac 100644
> --- a/lib/acpi.h
> +++ b/lib/acpi.h
> @@ -14,6 +14,7 @@
>   
>   #define RSDP_SIGNATURE ACPI_SIGNATURE('R','S','D','P')
>   #define RSDT_SIGNATURE ACPI_SIGNATURE('R','S','D','T')
> +#define XSDT_SIGNATURE ACPI_SIGNATURE('X','S','D','T')
>   #define FACP_SIGNATURE ACPI_SIGNATURE('F','A','C','P')
>   #define FACS_SIGNATURE ACPI_SIGNATURE('F','A','C','S')
>   
> @@ -56,6 +57,11 @@ struct acpi_table_rsdt_rev1 {
>   	u32 table_offset_entry[];
>   };
>   
> +struct acpi_table_xsdt {
> +	ACPI_TABLE_HEADER_DEF
> +	u64 table_offset_entry[];
> +};
> +
>   struct acpi_table_fadt_rev1 {
>   	ACPI_TABLE_HEADER_DEF	/* ACPI common table header */
>   	u32 firmware_ctrl;	/* Physical address of FACS */
> diff --git a/lib/acpi.c b/lib/acpi.c
> index 166ffd14..d35f09a6 100644
> --- a/lib/acpi.c
> +++ b/lib/acpi.c
> @@ -37,7 +37,8 @@ static struct acpi_table_rsdp *get_rsdp(void)
>   
>   void *find_acpi_table_addr(u32 sig)
>   {
> -	struct acpi_table_rsdt_rev1 *rsdt;
> +	struct acpi_table_rsdt_rev1 *rsdt = NULL;
> +	struct acpi_table_xsdt *xsdt = NULL;
>   	struct acpi_table_rsdp *rsdp;
>   	void *end;
>   	int i;
> @@ -62,18 +63,41 @@ void *find_acpi_table_addr(u32 sig)
>   		return rsdp;
>   
>   	rsdt = (void *)(ulong) rsdp->rsdt_physical_address;
> -	if (!rsdt || rsdt->signature != RSDT_SIGNATURE)
> -		return NULL;
> +	if (rsdt && rsdt->signature != RSDT_SIGNATURE)
> +		rsdt = NULL;
>   
>   	if (sig == RSDT_SIGNATURE)
>   		return rsdt;
>   
> -	end = (void *)rsdt + rsdt->length;
> -	for (i = 0; (void *)&rsdt->table_offset_entry[i] < end; i++) {
> -		struct acpi_table *t = (void *)(ulong) rsdt->table_offset_entry[i];
> +	if (rsdp->revision >= 2) {
> +		xsdt = (void *)rsdp->xsdt_physical_address;
> +		if (xsdt && xsdt->signature != XSDT_SIGNATURE)
> +			xsdt = NULL;
> +	}
>   
> -		if (t && t->signature == sig)
> -			return t;
> +	if (sig == XSDT_SIGNATURE)
> +		return xsdt;
> +
> +	/*
> +	 * When the system implements APCI 2.0 and above and XSDT is valid we
> +	 * have use XSDT to find other ACPI tables, otherwise, we use RSDT.
> +	 */
> +	if (xsdt) {
> +		end = (void *)xsdt + xsdt->length;
> +		for (i = 0; (void *)&xsdt->table_offset_entry[i] < end; i++) {
> +			struct acpi_table *t = (void *)(ulong) xsdt->table_offset_entry[i];
> +
> +			if (t && t->signature == sig)
> +				return t;
> +		}
> +	} else if (rsdt) {
> +		end = (void *)rsdt + rsdt->length;
> +		for (i = 0; (void *)&rsdt->table_offset_entry[i] < end; i++) {
> +			struct acpi_table *t = (void *)(ulong) rsdt->table_offset_entry[i];
> +
> +			if (t && t->signature == sig)
> +				return t;
> +		}
>   	}
>   
>   	return NULL;

-- 
Shaoqin