On 21/07/2025 10:31, Hari Limaye wrote:
> From: Penny Zheng <penny.zh...@arm.com>
>
> This commit expands xen_mpumap_update/xen_mpumap_update_entry to include
> destroying an existing entry.
>
> We define a new helper "disable_mpu_region_from_index" to disable the MPU
> region based on index. If region is within [0, 31], we could quickly
> disable the MPU region through PRENR_EL2 which provides direct access to the
> PRLAR_EL2.EN bits of EL2 MPU regions.
>
> Rignt now, we only support destroying a *WHOLE* MPU memory region,
> part-region removing is not supported, as in worst case, it will
> leave two fragments behind.
>
> Signed-off-by: Penny Zheng <penny.zh...@arm.com>
> Signed-off-by: Wei Chen <wei.c...@arm.com>
> Signed-off-by: Luca Fancellu <luca.fance...@arm.com>
> Signed-off-by: Hari Limaye <hari.lim...@arm.com>
> ---
> Changes from v1:
> - Move check for part-region removal outside if condition
> - Use normal printk
>
> Changes from v2:
> - Fix assert from `ASSERT(s <= e)` -> `ASSERT(s < e)`
> - Remove call to context_sync_mpu
> - Use register_t
> - Improve sanity checking to catch modification & removing non-existent
> entries
> - Update check for MPUMAP_REGION_INCLUSIVE to be generic
>
> Changes from v3:
> - Move early return for modifying case above MPUMAP_REGION_INCLUSIVE
> check
> - Add bool variable to store `flags & _PAGE_PRESENT`
> - Remove calls to `virt_to_maddr`
> ---
> xen/arch/arm/include/asm/mpu.h | 2 +
> xen/arch/arm/include/asm/mpu/cpregs.h | 4 ++
> xen/arch/arm/mpu/mm.c | 95 ++++++++++++++++++++++++---
> 3 files changed, 92 insertions(+), 9 deletions(-)
>
> diff --git a/xen/arch/arm/include/asm/mpu.h b/xen/arch/arm/include/asm/mpu.h
> index 63560c613b..5053edaf63 100644
> --- a/xen/arch/arm/include/asm/mpu.h
> +++ b/xen/arch/arm/include/asm/mpu.h
> @@ -23,6 +23,8 @@
> #define NUM_MPU_REGIONS_MASK (NUM_MPU_REGIONS - 1)
> #define MAX_MPU_REGION_NR NUM_MPU_REGIONS_MASK
>
> +#define PRENR_MASK GENMASK(31, 0)
> +
> #ifndef __ASSEMBLY__
>
> /*
> diff --git a/xen/arch/arm/include/asm/mpu/cpregs.h
> b/xen/arch/arm/include/asm/mpu/cpregs.h
> index bb15e02df6..9f3b32acd7 100644
> --- a/xen/arch/arm/include/asm/mpu/cpregs.h
> +++ b/xen/arch/arm/include/asm/mpu/cpregs.h
> @@ -6,6 +6,9 @@
> /* CP15 CR0: MPU Type Register */
> #define HMPUIR p15,4,c0,c0,4
>
> +/* CP15 CR6: Protection Region Enable Register */
> +#define HPRENR p15,4,c6,c1,1
> +
> /* CP15 CR6: MPU Protection Region Base/Limit/Select Address Register */
> #define HPRSELR p15,4,c6,c2,1
> #define HPRBAR p15,4,c6,c3,0
> @@ -82,6 +85,7 @@
> /* Alphabetically... */
> #define MPUIR_EL2 HMPUIR
> #define PRBAR_EL2 HPRBAR
> +#define PRENR_EL2 HPRENR
> #define PRLAR_EL2 HPRLAR
> #define PRSELR_EL2 HPRSELR
> #endif /* CONFIG_ARM_32 */
> diff --git a/xen/arch/arm/mpu/mm.c b/xen/arch/arm/mpu/mm.c
> index d5426525af..2154b3720d 100644
> --- a/xen/arch/arm/mpu/mm.c
> +++ b/xen/arch/arm/mpu/mm.c
> @@ -189,6 +189,42 @@ static int xen_mpumap_alloc_entry(uint8_t *idx)
> return 0;
> }
>
> +/*
> + * Disable and remove an MPU region from the data structure and MPU
> registers.
> + *
> + * @param index Index of the MPU region to be disabled.
> + */
> +static void disable_mpu_region_from_index(uint8_t index)
> +{
> + ASSERT(spin_is_locked(&xen_mpumap_lock));
> + ASSERT(index != INVALID_REGION_IDX);
> +
> + if ( !region_is_valid(&xen_mpumap[index]) )
> + {
> + printk(XENLOG_WARNING
> + "mpu: MPU memory region[%u] is already disabled\n", index);
NIT: In this patch you start adding mpu: prefix, even though other messages do
not have it. I don't think it's needed.
Otherwise:
Reviewed-by: Michal Orzel <michal.or...@amd.com>
~Michal
