Hi Luca,
On 07/04/2025 10:14, Luca Fancellu wrote:
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Implement the function setup_mpu that will logically track the MPU
regions defined by hardware registers, start introducing data
structures and functions to track the status from the C world.
The xen_mpumap_mask bitmap is used to track which MPU region are
enabled at runtime.
This function is called from setup_mm() which full implementation
will be provided in a later stage.
Signed-off-by: Luca Fancellu <luca.fance...@arm.com>
---
xen/arch/arm/include/asm/arm64/mpu.h | 2 ++
xen/arch/arm/mpu/mm.c | 49 +++++++++++++++++++++++++++-
2 files changed, 50 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/include/asm/arm64/mpu.h
b/xen/arch/arm/include/asm/arm64/mpu.h
index 7cf8d355a1af..ff5a957bf085 100644
--- a/xen/arch/arm/include/asm/arm64/mpu.h
+++ b/xen/arch/arm/include/asm/arm64/mpu.h
@@ -6,6 +6,8 @@
#ifndef __ARM_ARM64_MPU_H__
#define __ARM_ARM64_MPU_H__
+#define PRENR_MASK GENMASK(31, 0)
This can be moved to xen/arch/arm/include/asm/mpu.h
+
/*
* Excute never.
* Stage 1 EL2 translation regime.
diff --git a/xen/arch/arm/mpu/mm.c b/xen/arch/arm/mpu/mm.c
index 2c5820a44f13..fe05c8097155 100644
--- a/xen/arch/arm/mpu/mm.c
+++ b/xen/arch/arm/mpu/mm.c
@@ -14,6 +14,17 @@
struct page_info *frame_table;
+/* Maximum number of supported MPU memory regions by the EL2 MPU. */
+uint8_t __ro_after_init max_xen_mpumap;
+
+/*
+ * Bitmap xen_mpumap_mask is to record the usage of EL2 MPU memory regions.
+ * Bit 0 represents MPU memory region 0, bit 1 represents MPU memory
+ * region 1, ..., and so on.
+ * If a MPU memory region gets enabled, set the according bit to 1.
+ */
+DECLARE_BITMAP(xen_mpumap_mask, MAX_MPU_REGIONS);
+
/* EL2 Xen MPU memory region mapping table. */
pr_t xen_mpumap[MAX_MPU_REGIONS];
@@ -224,9 +235,45 @@ pr_t pr_of_xenaddr(paddr_t base, paddr_t limit, unsigned
attr)
return region;
}
+/*
+ * The code in this function needs to track the regions programmed in
+ * arm64/mpu/head.S
+ */
+static void __init setup_mpu(void)
+{
+ register_t prenr;
+ unsigned int i = 0;
+
+ /*
+ * MPUIR_EL2.Region[0:7] identifies the number of regions supported by
+ * the EL2 MPU.
+ */
+ max_xen_mpumap = (uint8_t)(READ_SYSREG(MPUIR_EL2) & NUM_MPU_REGIONS_MASK);
+
+ /* PRENR_EL2 has the N bit set if the N region is enabled, N < 32 */
+ prenr = (READ_SYSREG(PRENR_EL2) & PRENR_MASK);
+
+ /*
+ * Set the bitfield for regions enabled in assembly boot-time.
+ * This code works under the assumption that the code in head.S has
+ * allocated and enabled regions below 32 (N < 32).
+ */
+ while ( prenr > 0 )
+ {
+ if (prenr & 0x1)
+ {
+ set_bit(i, xen_mpumap_mask);
+ read_protection_region(&xen_mpumap[i], i);
+ }
+
+ prenr >>= 1;
+ i++;
+ }
+}
+
void __init setup_mm(void)
{
- BUG_ON("unimplemented");
+ setup_mpu();
}
int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
--
2.34.1
- Ayan
