On 26/02/2025 18:30, Ariel D'Alessandro wrote:
> Bifrost MMUs support AArch64 4kB granule specification. However,
> panfrost only enables MMU in legacy mode, despite the presence of the
> HW_FEATURE_AARCH64_MMU feature flag.
>
> This commit adds support to use page tables according to AArch64 4kB
> granule specification. This feature is enabled conditionally based on
> the GPU model's HW_FEATURE_AARCH64_MMU feature flag.
>
> Signed-off-by: Ariel D'Alessandro <ariel.dalessan...@collabora.com>
I find some of the naming confusing here. The subject calls it
'ARM_64_LPAE_S1' which in an unfortunate name from the iommu code.
AIUI, LPAE is the "Large Physical Address Extension" and is a v7 feature
for 32 bit. "LEGACY" (as Bifrost calls it) mode is a (modified) version
of LPAE, which in Linux we've called "mali_lpae".
What you're adding support for is AARCH64_4K which is the v8 64 bit
mode. So I think it's worth including the "64" part of the name of the
mmu_lpae_s1_enable() function. Personally I'd be tempted to drop the
"_s1" part, but I guess there's a small chance someone will find a use
for the second stage one day.
Note also that it's not necessarily a clear-cut improvement to use
AARCH64_4K over LEGACY. I wouldn't be surprised if this actually causes
(minor) performance regressions on some platforms. Sadly I don't have
access to a range of hardware to test this on.
Steve
> ---
> drivers/gpu/drm/panfrost/panfrost_device.h | 1 +
> drivers/gpu/drm/panfrost/panfrost_mmu.c | 118 +++++++++++++++++----
> drivers/gpu/drm/panfrost/panfrost_regs.h | 29 +++++
> 3 files changed, 128 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h
> b/drivers/gpu/drm/panfrost/panfrost_device.h
> index cffcb0ac7c11..dea252f43c58 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_device.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_device.h
> @@ -153,6 +153,7 @@ struct panfrost_device {
> };
>
> struct panfrost_mmu {
> + void (*enable)(struct panfrost_device *pfdev, struct panfrost_mmu *mmu);
> struct panfrost_device *pfdev;
> struct kref refcount;
> struct io_pgtable_cfg pgtbl_cfg;
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index 7df2c8d5b0ae..30b8e2723254 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -26,6 +26,48 @@
> #define mmu_write(dev, reg, data) writel(data, dev->iomem + reg)
> #define mmu_read(dev, reg) readl(dev->iomem + reg)
>
> +static u64 mair_to_memattr(u64 mair, bool coherent)
> +{
> + u64 memattr = 0;
> + u32 i;
> +
> + for (i = 0; i < 8; i++) {
> + u8 in_attr = mair >> (8 * i), out_attr;
> + u8 outer = in_attr >> 4, inner = in_attr & 0xf;
> +
> + /* For caching to be enabled, inner and outer caching policy
> + * have to be both write-back, if one of them is write-through
> + * or non-cacheable, we just choose non-cacheable. Device
> + * memory is also translated to non-cacheable.
> + */
> + if (!(outer & 3) || !(outer & 4) || !(inner & 4)) {
> + out_attr = AS_MEMATTR_AARCH64_INNER_OUTER_NC |
> + AS_MEMATTR_AARCH64_SH_MIDGARD_INNER |
> + AS_MEMATTR_AARCH64_INNER_ALLOC_EXPL(false,
> false);
> + } else {
> + out_attr = AS_MEMATTR_AARCH64_INNER_OUTER_WB |
> + AS_MEMATTR_AARCH64_INNER_ALLOC_EXPL(inner &
> 1, inner & 2);
> + /* Use SH_MIDGARD_INNER mode when device isn't coherent,
> + * so SH_IS, which is used when IOMMU_CACHE is set, maps
> + * to Mali's internal-shareable mode. As per the Mali
> + * Spec, inner and outer-shareable modes aren't allowed
> + * for WB memory when coherency is disabled.
> + * Use SH_CPU_INNER mode when coherency is enabled, so
> + * that SH_IS actually maps to the standard definition
> of
> + * inner-shareable.
> + */
> + if (!coherent)
> + out_attr |= AS_MEMATTR_AARCH64_SH_MIDGARD_INNER;
> + else
> + out_attr |= AS_MEMATTR_AARCH64_SH_CPU_INNER;
> + }
> +
> + memattr |= (u64)out_attr << (8 * i);
> + }
> +
> + return memattr;
> +}
> +
> static int wait_ready(struct panfrost_device *pfdev, u32 as_nr)
> {
> int ret;
> @@ -121,38 +163,66 @@ static int mmu_hw_do_operation(struct panfrost_device
> *pfdev,
> return ret;
> }
>
> -static void panfrost_mmu_enable(struct panfrost_device *pfdev, struct
> panfrost_mmu *mmu)
> +static void
> +_panfrost_mmu_as_control_write(struct panfrost_device *pfdev, u32 as_nr,
> + u64 transtab, u64 memattr, u64 transcfg)
> {
> - int as_nr = mmu->as;
> - struct io_pgtable_cfg *cfg = &mmu->pgtbl_cfg;
> - u64 transtab = cfg->arm_mali_lpae_cfg.transtab;
> - u64 memattr = cfg->arm_mali_lpae_cfg.memattr;
> -
> mmu_hw_do_operation_locked(pfdev, as_nr, 0, ~0ULL,
> AS_COMMAND_FLUSH_MEM);
>
> mmu_write(pfdev, AS_TRANSTAB_LO(as_nr), lower_32_bits(transtab));
> mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), upper_32_bits(transtab));
>
> - /* Need to revisit mem attrs.
> - * NC is the default, Mali driver is inner WT.
> - */
> mmu_write(pfdev, AS_MEMATTR_LO(as_nr), lower_32_bits(memattr));
> mmu_write(pfdev, AS_MEMATTR_HI(as_nr), upper_32_bits(memattr));
>
> + mmu_write(pfdev, AS_TRANSCFG_LO(as_nr), lower_32_bits(transcfg));
> + mmu_write(pfdev, AS_TRANSCFG_HI(as_nr), upper_32_bits(transcfg));
> +
> write_cmd(pfdev, as_nr, AS_COMMAND_UPDATE);
> +
> + dev_dbg(pfdev->dev, "mmu_as_control: as=%d, transtab=0x%016llx,
> memattr=0x%016llx, transcfg=0x%016llx",
> + as_nr, transtab, memattr, transcfg);
> }
>
> -static void panfrost_mmu_disable(struct panfrost_device *pfdev, u32 as_nr)
> +static void mmu_lpae_s1_enable(struct panfrost_device *pfdev,
> + struct panfrost_mmu *mmu)
> {
> - mmu_hw_do_operation_locked(pfdev, as_nr, 0, ~0ULL,
> AS_COMMAND_FLUSH_MEM);
> + struct io_pgtable_cfg *cfg = &mmu->pgtbl_cfg;
> + int as_nr = mmu->as;
>
> - mmu_write(pfdev, AS_TRANSTAB_LO(as_nr), 0);
> - mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), 0);
> + u64 transtab =
> + cfg->arm_lpae_s1_cfg.ttbr & AS_TRANSTAB_LPAE_ADDR_SPACE_MASK;
> + u64 memattr =
> + mair_to_memattr(cfg->arm_lpae_s1_cfg.mair, pfdev->coherent);
> + u32 va_bits = GPU_MMU_FEATURES_VA_BITS(pfdev->features.mmu_features);
> + u64 transcfg = AS_TRANSCFG_PTW_MEMATTR_WB |
> + AS_TRANSCFG_PTW_RA |
> + AS_TRANSCFG_ADRMODE_AARCH64_4K |
> + AS_TRANSCFG_INA_BITS(55 - va_bits);
>
> - mmu_write(pfdev, AS_MEMATTR_LO(as_nr), 0);
> - mmu_write(pfdev, AS_MEMATTR_HI(as_nr), 0);
> + if (pfdev->coherent)
> + transcfg |= AS_TRANSCFG_PTW_SH_OS;
>
> - write_cmd(pfdev, as_nr, AS_COMMAND_UPDATE);
> + _panfrost_mmu_as_control_write(pfdev, as_nr, transtab, memattr,
> + transcfg);
> +}
> +
> +static void mmu_mali_lpae_enable(struct panfrost_device *pfdev,
> + struct panfrost_mmu *mmu)
> +{
> + struct io_pgtable_cfg *cfg = &mmu->pgtbl_cfg;
> + int as_nr = mmu->as;
> +
> + _panfrost_mmu_as_control_write(pfdev, as_nr,
> + cfg->arm_mali_lpae_cfg.transtab,
> + cfg->arm_mali_lpae_cfg.memattr,
> + AS_TRANSCFG_ADRMODE_LEGACY);
> +}
> +
> +static void panfrost_mmu_disable(struct panfrost_device *pfdev, u32 as_nr)
> +{
> + _panfrost_mmu_as_control_write(pfdev, as_nr, 0, 0,
> + AS_TRANSCFG_ADRMODE_UNMAPPED);
> }
>
> u32 panfrost_mmu_as_get(struct panfrost_device *pfdev, struct panfrost_mmu
> *mmu)
> @@ -182,7 +252,7 @@ u32 panfrost_mmu_as_get(struct panfrost_device *pfdev,
> struct panfrost_mmu *mmu)
> mmu_write(pfdev, MMU_INT_CLEAR, mask);
> mmu_write(pfdev, MMU_INT_MASK, ~pfdev->as_faulty_mask);
> pfdev->as_faulty_mask &= ~mask;
> - panfrost_mmu_enable(pfdev, mmu);
> + mmu->enable(pfdev, mmu);
> }
>
> goto out;
> @@ -214,7 +284,7 @@ u32 panfrost_mmu_as_get(struct panfrost_device *pfdev,
> struct panfrost_mmu *mmu)
>
> dev_dbg(pfdev->dev, "Assigned AS%d to mmu %p, alloc_mask=%lx", as, mmu,
> pfdev->as_alloc_mask);
>
> - panfrost_mmu_enable(pfdev, mmu);
> + mmu->enable(pfdev, mmu);
>
> out:
> spin_unlock(&pfdev->as_lock);
> @@ -618,6 +688,7 @@ struct panfrost_mmu *panfrost_mmu_ctx_create(struct
> panfrost_device *pfdev)
> u32 va_bits = GPU_MMU_FEATURES_VA_BITS(pfdev->features.mmu_features);
> u32 pa_bits = GPU_MMU_FEATURES_PA_BITS(pfdev->features.mmu_features);
> struct panfrost_mmu *mmu;
> + enum io_pgtable_fmt fmt;
>
> mmu = kzalloc(sizeof(*mmu), GFP_KERNEL);
> if (!mmu)
> @@ -642,8 +713,15 @@ struct panfrost_mmu *panfrost_mmu_ctx_create(struct
> panfrost_device *pfdev)
> .iommu_dev = pfdev->dev,
> };
>
> - mmu->pgtbl_ops = alloc_io_pgtable_ops(ARM_MALI_LPAE, &mmu->pgtbl_cfg,
> - mmu);
> + if (panfrost_has_hw_feature(pfdev, HW_FEATURE_AARCH64_MMU)) {
> + fmt = ARM_64_LPAE_S1;
> + mmu->enable = mmu_lpae_s1_enable;
> + } else {
> + fmt = ARM_MALI_LPAE;
> + mmu->enable = mmu_mali_lpae_enable;
> + }
> + mmu->pgtbl_ops = alloc_io_pgtable_ops(fmt, &mmu->pgtbl_cfg, mmu);
> +
> if (!mmu->pgtbl_ops) {
> kfree(mmu);
> return ERR_PTR(-EINVAL);
> diff --git a/drivers/gpu/drm/panfrost/panfrost_regs.h
> b/drivers/gpu/drm/panfrost/panfrost_regs.h
> index 4e6064d5feaa..a5ca36f583ff 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_regs.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_regs.h
> @@ -301,6 +301,17 @@
> #define AS_TRANSTAB_HI(as) (MMU_AS(as) + 0x04) /* (RW) Translation
> Table Base Address for address space n, high word */
> #define AS_MEMATTR_LO(as) (MMU_AS(as) + 0x08) /* (RW) Memory
> attributes for address space n, low word. */
> #define AS_MEMATTR_HI(as) (MMU_AS(as) + 0x0C) /* (RW) Memory
> attributes for address space n, high word. */
> +#define AS_MEMATTR_AARCH64_INNER_ALLOC_IMPL (2 << 2)
> +#define AS_MEMATTR_AARCH64_INNER_ALLOC_EXPL(w, r) ((3 << 2) | \
> + ((w) ? BIT(0) : 0) | \
> + ((r) ? BIT(1) : 0))
> +#define AS_MEMATTR_AARCH64_SH_MIDGARD_INNER (0 << 4)
> +#define AS_MEMATTR_AARCH64_SH_CPU_INNER (1 << 4)
> +#define AS_MEMATTR_AARCH64_SH_CPU_INNER_SHADER_COH (2 << 4)
> +#define AS_MEMATTR_AARCH64_SHARED (0 << 6)
> +#define AS_MEMATTR_AARCH64_INNER_OUTER_NC (1 << 6)
> +#define AS_MEMATTR_AARCH64_INNER_OUTER_WB (2 << 6)
> +#define AS_MEMATTR_AARCH64_FAULT (3 << 6)
> #define AS_LOCKADDR_LO(as) (MMU_AS(as) + 0x10) /* (RW) Lock region
> address for address space n, low word */
> #define AS_LOCKADDR_HI(as) (MMU_AS(as) + 0x14) /* (RW) Lock region
> address for address space n, high word */
> #define AS_COMMAND(as) (MMU_AS(as) + 0x18) /* (WO) MMU
> command register for address space n */
> @@ -311,6 +322,24 @@
> /* Additional Bifrost AS registers */
> #define AS_TRANSCFG_LO(as) (MMU_AS(as) + 0x30) /* (RW) Translation
> table configuration for address space n, low word */
> #define AS_TRANSCFG_HI(as) (MMU_AS(as) + 0x34) /* (RW) Translation
> table configuration for address space n, high word */
> +#define AS_TRANSCFG_ADRMODE_LEGACY (0 << 0)
> +#define AS_TRANSCFG_ADRMODE_UNMAPPED (1 << 0)
> +#define AS_TRANSCFG_ADRMODE_IDENTITY (2 << 0)
> +#define AS_TRANSCFG_ADRMODE_AARCH64_4K (6 << 0)
> +#define AS_TRANSCFG_ADRMODE_AARCH64_64K (8 << 0)
> +#define AS_TRANSCFG_INA_BITS(x) ((x) << 6)
> +#define AS_TRANSCFG_OUTA_BITS(x) ((x) << 14)
> +#define AS_TRANSCFG_SL_CONCAT BIT(22)
> +#define AS_TRANSCFG_PTW_MEMATTR_NC (1 << 24)
> +#define AS_TRANSCFG_PTW_MEMATTR_WB (2 << 24)
> +#define AS_TRANSCFG_PTW_SH_NS (0 << 28)
> +#define AS_TRANSCFG_PTW_SH_OS (2 << 28)
> +#define AS_TRANSCFG_PTW_SH_IS (3 << 28)
> +#define AS_TRANSCFG_PTW_RA BIT(30)
> +#define AS_TRANSCFG_DISABLE_HIER_AP BIT(33)
> +#define AS_TRANSCFG_DISABLE_AF_FAULT BIT(34)
> +#define AS_TRANSCFG_WXN BIT(35)
> +#define AS_TRANSCFG_XREADABLE BIT(36)
> #define AS_FAULTEXTRA_LO(as) (MMU_AS(as) + 0x38) /* (RO) Secondary
> fault address for address space n, low word */
> #define AS_FAULTEXTRA_HI(as) (MMU_AS(as) + 0x3C) /* (RO) Secondary
> fault address for address space n, high word */
>
