RE: [PATCH v2] irqchip/gic-v3: workaround for ASR8601 when reading mpidr

[Yan Zheng（严政）]

> -----Original Message-----
> From: Marc Zyngier [mailto:maz@xxxxxxxxxx]
> Sent: Monday, May 29, 2023 11:02 PM
> To: Yan Zheng（严政） <zhengyan@xxxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx; Gao Meitao（高玫涛）
> <meitaogao@xxxxxxxxxxxx>; Zhou Qiao(周侨) <qiaozhou@xxxxxxxxxxxx>;
> tglx@xxxxxxxxxxxxx; Zhang Zhizhou(张治洲) <zhizhouzhang@xxxxxxxxxxxx>
> Subject: Re: [PATCH v2] irqchip/gic-v3: workaround for ASR8601 when reading
> mpidr
> 
> On Mon, 22 May 2023 12:06:43 +0100,
> zhengyan <zhengyan@xxxxxxxxxxxx> wrote:
> >
> > This patch add workaround for ASR8601, which uses an armv8.2 processor
> > with a gic-500. But gic-500 is incompatible with
> > ARMv8.2 implementations from ARM.
> >
> > ARMv8.2 from ARM implementation uses Multiprocessor Affinity Register
> > to identify the logical address of the core by
> > | cluster | core | thread |.
> > However, gic-500 only supports topologies with affinity levels less
> > than 2 as
> > | cluster | core|.
> >
> > So we need this patch as workaround to shift the MPIDR values to
> > ensure proper functionality
> >
> > Signed-off-by: zhengyan <zhengyan@xxxxxxxxxxxx>
> > ---
> >  Documentation/arm64/silicon-errata.rst |  4 ++++
> >  drivers/irqchip/irq-gic-v3.c           | 30
> ++++++++++++++++++++++++++
> >  2 files changed, 34 insertions(+)
> >
> > diff --git a/Documentation/arm64/silicon-errata.rst
> > b/Documentation/arm64/silicon-errata.rst
> > index 9e311bc43e05..d6430ade349d 100644
> > --- a/Documentation/arm64/silicon-errata.rst
> > +++ b/Documentation/arm64/silicon-errata.rst
> > @@ -214,3 +214,7 @@ stable kernels.
> >  +----------------+-----------------+-----------------+-----------------------------+
> >  | Fujitsu        | A64FX           | E#010001        |
> FUJITSU_ERRATUM_010001      |
> >
> > +----------------+-----------------+-----------------+----------------
> > -------------+
> > +
> > ++----------------+-----------------+-----------------+-----------------------------+
> > +| ASR            | ASR8601         | #8601001        | N/A
> |
> > ++----------------+-----------------+-----------------+-----------------------------+
> > diff --git a/drivers/irqchip/irq-gic-v3.c
> > b/drivers/irqchip/irq-gic-v3.c index 6fcee221f201..cf64783dfe70 100644
> > --- a/drivers/irqchip/irq-gic-v3.c
> > +++ b/drivers/irqchip/irq-gic-v3.c
> > @@ -39,6 +39,9 @@
> >
> >  #define FLAGS_WORKAROUND_GICR_WAKER_MSM8996	(1ULL << 0)
> >  #define FLAGS_WORKAROUND_CAVIUM_ERRATUM_38539	(1ULL << 1)
> > +#define FLAGS_WORKAROUND_ASR_ERRATUM_8601001	(1ULL << 2)
> > +
> > +#define ASR8601_AFF_QUIRK(aff)			(aff >> 8)
> 
> This is wrong. There are more than just affinity bits in MPIDR, and you're making
> a mess of the result.
> 

Yes, I made a mistake here.

> >
> >  #define GIC_IRQ_TYPE_PARTITION	(GIC_IRQ_TYPE_LPI + 1)
> >
> > @@ -659,6 +662,9 @@ static u64 gic_mpidr_to_affinity(unsigned long
> > mpidr)  {
> >  	u64 aff;
> >
> > +	if (gic_data.flags & FLAGS_WORKAROUND_ASR_ERRATUM_8601001)
> > +		mpidr = ASR8601_AFF_QUIRK(mpidr);
> > +
> >  	aff = ((u64)MPIDR_AFFINITY_LEVEL(mpidr, 3) << 32 |
> >  	       MPIDR_AFFINITY_LEVEL(mpidr, 2) << 16 |
> >  	       MPIDR_AFFINITY_LEVEL(mpidr, 1) << 8  | @@ -970,6 +976,9
> @@
> > static int __gic_populate_rdist(struct redist_region *region, void __iomem
> *ptr)
> >  	 * Convert affinity to a 32bit value that can be matched to
> >  	 * GICR_TYPER bits [63:32].
> >  	 */
> > +	if (gic_data.flags & FLAGS_WORKAROUND_ASR_ERRATUM_8601001)
> > +		mpidr = ASR8601_AFF_QUIRK(mpidr);
> 
> It really wasn't what I had in mind when I asked you to place this inside a helper.
> The whole thing looks horrible, and I really don't want to have to maintain
> anything like it.
> 
> I came up with the following patch, which keeps the workaround *in a single
> spot*.
> 
> Let me know if that works for you.
> 
> 	M.
> 

Really thanks for your help, this patch works well for us.
My previous patch was too ugly, this one looks better. I didn't find this good solution.
Should I send a patch for v3, considering that you're the author?

> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c index
> 6fcee221f201..b7d69ef4da9f 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -39,6 +39,7 @@
> 
>  #define FLAGS_WORKAROUND_GICR_WAKER_MSM8996	(1ULL << 0)
>  #define FLAGS_WORKAROUND_CAVIUM_ERRATUM_38539	(1ULL << 1)
> +#define FLAGS_WORKAROUND_ASR_ERRATUM_8601001	(1ULL << 2)
> 
>  #define GIC_IRQ_TYPE_PARTITION	(GIC_IRQ_TYPE_LPI + 1)
> 
> @@ -655,10 +656,16 @@ static int gic_irq_set_vcpu_affinity(struct irq_data *d,
> void *vcpu)
>  	return 0;
>  }
> 
> -static u64 gic_mpidr_to_affinity(unsigned long mpidr)
> +static u64 gic_cpu_to_affinity(int cpu)
>  {
> +	u64 mpidr = cpu_logical_map(cpu);
>  	u64 aff;
> 
> +	/* ASR8601 needs to have its affinities shifted down... */
> +	if (unlikely(gic_data.flags &
> FLAGS_WORKAROUND_ASR_ERRATUM_8601001))
> +		mpidr = (MPIDR_AFFINITY_LEVEL(mpidr, 1)	|
> +			 (MPIDR_AFFINITY_LEVEL(mpidr, 2) << 8));
> +
>  	aff = ((u64)MPIDR_AFFINITY_LEVEL(mpidr, 3) << 32 |
>  	       MPIDR_AFFINITY_LEVEL(mpidr, 2) << 16 |
>  	       MPIDR_AFFINITY_LEVEL(mpidr, 1) << 8  | @@ -913,7 +920,7
> @@ static void __init gic_dist_init(void)
>  	 * Set all global interrupts to the boot CPU only. ARE must be
>  	 * enabled.
>  	 */
> -	affinity = gic_mpidr_to_affinity(cpu_logical_map(smp_processor_id()));
> +	affinity = gic_cpu_to_affinity(smp_processor_id());
>  	for (i = 32; i < GIC_LINE_NR; i++)
>  		gic_write_irouter(affinity, base + GICD_IROUTER + i * 8);
> 
> @@ -962,7 +969,7 @@ static int gic_iterate_rdists(int (*fn)(struct
> redist_region *, void __iomem *))
> 
>  static int __gic_populate_rdist(struct redist_region *region, void __iomem
> *ptr)  {
> -	unsigned long mpidr = cpu_logical_map(smp_processor_id());
> +	unsigned long mpidr;
>  	u64 typer;
>  	u32 aff;
> 
> @@ -970,6 +977,8 @@ static int __gic_populate_rdist(struct redist_region
> *region, void __iomem *ptr)
>  	 * Convert affinity to a 32bit value that can be matched to
>  	 * GICR_TYPER bits [63:32].
>  	 */
> +	mpidr = gic_cpu_to_affinity(smp_processor_id());
> +
>  	aff = (MPIDR_AFFINITY_LEVEL(mpidr, 3) << 24 |
>  	       MPIDR_AFFINITY_LEVEL(mpidr, 2) << 16 |
>  	       MPIDR_AFFINITY_LEVEL(mpidr, 1) << 8 | @@ -1262,9 +1271,11
> @@ static u16 gic_compute_target_list(int *base_cpu, const struct cpumask
> *mask,
>  				   unsigned long cluster_id)
>  {
>  	int next_cpu, cpu = *base_cpu;
> -	unsigned long mpidr = cpu_logical_map(cpu);
> +	unsigned long mpidr;
>  	u16 tlist = 0;
> 
> +	mpidr = gic_cpu_to_affinity(cpu);
> +
>  	while (cpu < nr_cpu_ids) {
>  		tlist |= 1 << (mpidr & 0xf);
> 
> @@ -1273,8 +1284,7 @@ static u16 gic_compute_target_list(int *base_cpu,
> const struct cpumask *mask,
>  			goto out;
>  		cpu = next_cpu;
> 
> -		mpidr = cpu_logical_map(cpu);
> -
> +		mpidr = gic_cpu_to_affinity(cpu);
>  		if (cluster_id != MPIDR_TO_SGI_CLUSTER_ID(mpidr)) {
>  			cpu--;
>  			goto out;
> @@ -1318,7 +1328,7 @@ static void gic_ipi_send_mask(struct irq_data *d,
> const struct cpumask *mask)
>  	dsb(ishst);
> 
>  	for_each_cpu(cpu, mask) {
> -		u64 cluster_id = MPIDR_TO_SGI_CLUSTER_ID(cpu_logical_map(cpu));
> +		u64 cluster_id =
> MPIDR_TO_SGI_CLUSTER_ID(gic_cpu_to_affinity(cpu));
>  		u16 tlist;
> 
>  		tlist = gic_compute_target_list(&cpu, mask, cluster_id); @@ -1376,7
> +1386,7 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask
> *mask_val,
> 
>  	offset = convert_offset_index(d, GICD_IROUTER, &index);
>  	reg = gic_dist_base(d) + offset + (index * 8);
> -	val = gic_mpidr_to_affinity(cpu_logical_map(cpu));
> +	val = gic_cpu_to_affinity(cpu);
> 
>  	gic_write_irouter(val, reg);
> 
> @@ -1786,6 +1796,15 @@ static bool gic_enable_quirk_nvidia_t241(void
> *data)
>  	return true;
>  }
> 
> +static bool gic_enable_quirk_asr8601(void *data) {
> +	struct gic_chip_data *d = data;
> +
> +	d->flags |= FLAGS_WORKAROUND_ASR_ERRATUM_8601001;
> +
> +	return true;
> +}
> +
>  static const struct gic_quirk gic_quirks[] = {
>  	{
>  		.desc	= "GICv3: Qualcomm MSM8996 broken firmware",
> @@ -1823,6 +1842,11 @@ static const struct gic_quirk gic_quirks[] = {
>  		.mask	= 0xffffffff,
>  		.init	= gic_enable_quirk_nvidia_t241,
>  	},
> +	{
> +		.desc	= "GICv3: ASR erratum 8601001",
> +		.compatible = "asr,asr8601-gic-v3",
> +		.init	= gic_enable_quirk_asr8601,
> +	},
>  	{
>  	}
>  };
> 
> 
> --
> Without deviation from the norm, progress is not possible.