[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v3 34/52] xen/mpu: destroy an existing entry in Xen MPU memory mapping table
Hi Ayan On 2023/7/1 00:17, Ayan Kumar Halder wrote: On 26/06/2023 04:34, Penny Zheng wrote:CAUTION: This message has originated from an External Source. Please use proper judgment and caution when opening attachments, clicking links, or responding to this email.This commit expands xen_mpumap_update/xen_mpumap_update_entry to include destroying an existing entry.We define a new helper "control_xen_mpumap_region_from_index" to enable/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 thePRLAR_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.zheng@xxxxxxx> Signed-off-by: Wei Chen <wei.chen@xxxxxxx> --- v3: - make pr_get_base()/pr_get_limit() static inline - need an isb to ensure register write visible before zeroing the entry --- xen/arch/arm/include/asm/arm64/mpu.h | 2 + xen/arch/arm/include/asm/arm64/sysregs.h | 3 + xen/arch/arm/mm.c | 5 ++ xen/arch/arm/mpu/mm.c | 74 ++++++++++++++++++++++++ 4 files changed, 84 insertions(+)diff --git a/xen/arch/arm/include/asm/arm64/mpu.h b/xen/arch/arm/include/asm/arm64/mpu.hindex 715ea69884..aee7947223 100644 --- a/xen/arch/arm/include/asm/arm64/mpu.h +++ b/xen/arch/arm/include/asm/arm64/mpu.h @@ -25,6 +25,8 @@ #define REGION_UART_SEL 0x07 #define MPUIR_REGION_MASK ((_AC(1, UL) << 8) - 1) +#define MPU_PRENR_BITS 32This is common to R52 and R82.Thus, you can put it in the common file (may be xen/arch/arm/include/asm/mpu/mm.h) Will do. + /* Access permission attributes. */ /* Read/Write at EL2, No Access at EL1/EL0. */ #define AP_RW_EL2 0x0diff --git a/xen/arch/arm/include/asm/arm64/sysregs.h b/xen/arch/arm/include/asm/arm64/sysregs.hindex c8a679afdd..96c025053b 100644 --- a/xen/arch/arm/include/asm/arm64/sysregs.h +++ b/xen/arch/arm/include/asm/arm64/sysregs.h @@ -509,6 +509,9 @@ /* MPU Type registers encode */ #define MPUIR_EL2 S3_4_C0_C0_4 +/* MPU Protection Region Enable Register encode */ +#define PRENR_EL2 S3_4_C6_C1_1 + #endif /* Access to system registers */ diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c index 8625066256..247d17cfa1 100644 --- a/xen/arch/arm/mm.c +++ b/xen/arch/arm/mm.c@@ -164,7 +164,12 @@ int destroy_xen_mappings(unsigned long s, unsigned long e)ASSERT(IS_ALIGNED(s, PAGE_SIZE)); ASSERT(IS_ALIGNED(e, PAGE_SIZE)); ASSERT(s <= e); +#ifndef CONFIG_HAS_MPU return xen_pt_update(s, INVALID_MFN, (e - s) >> PAGE_SHIFT, 0); +#else + return xen_mpumap_update(virt_to_maddr((void *)s), + virt_to_maddr((void *)e), 0); +#endif }Refer my comment in previous patch.You can have two implementations of this function 1) xen/arch/arm/mmu/mm.c 2) xen/arch/arm/mpu/mm.h Refer my comment in previous patch. I prefer #ifdef in destroy_xen_mappings() int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int flags)diff --git a/xen/arch/arm/mpu/mm.c b/xen/arch/arm/mpu/mm.c index 0a65b58dc4..a40055ae5e 100644 --- a/xen/arch/arm/mpu/mm.c +++ b/xen/arch/arm/mpu/mm.c@@ -425,6 +425,59 @@ static int mpumap_contain_region(pr_t *table, uint8_t nr_regions,return MPUMAP_REGION_FAILED; } +/* Disable or enable EL2 MPU memory region at index #index */ +static void control_mpu_region_from_index(uint8_t index, bool enable) +{ + pr_t region; + + read_protection_region(®ion, index); + if ( !region_is_valid(®ion) ^ enable ) + { + printk(XENLOG_WARNING + "mpu: MPU memory region[%u] is already %s\n", index, + enable ? "enabled" : "disabled"); + return; + } + + /* + * ARM64v8R provides PRENR_EL2 to have direct access to the + * PRLAR_EL2.EN bits of EL2 MPU regions from 0 to 31. + */ + if ( index < MPU_PRENR_BITS ) + { + uint64_t orig, after; + + orig = READ_SYSREG(PRENR_EL2); + if ( enable ) + /* Set respective bit */ + after = orig | (1UL << index); + else + /* Clear respective bit */ + after = orig & (~(1UL << index)); + WRITE_SYSREG(after, PRENR_EL2); + } + else + { + region.prlar.reg.en = enable ? 1 : 0; + write_protection_region((const pr_t*)®ion, index); + } + /* Ensure the write before zeroing the entry */dsb(); /* to ensure write completes */+ isb(); + + /* Update according bitfield in xen_mpumap_mask */ + spin_lock(&xen_mpumap_alloc_lock); + + if ( enable ) + set_bit(index, xen_mpumap_mask); + else + { + clear_bit(index, xen_mpumap_mask); + memset(&xen_mpumap[index], 0, sizeof(pr_t)); + } + + spin_unlock(&xen_mpumap_alloc_lock); +} + /** Update an entry in Xen MPU memory region mapping table(xen_mpumap) at* the index @idx.@@ -461,6 +514,27 @@ static int xen_mpumap_update_entry(paddr_t base, paddr_t limit,write_protection_region((const pr_t*)(&xen_mpumap[idx]), idx); } + else + { + /*+ * Currently, 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.+ * part-region removing will be introduced only when actual usage+ * comes. + */ + if ( rc == MPUMAP_REGION_INCLUSIVE ) + {+ region_printk("mpu: part-region removing is not supported\n");+ return -EINVAL; + } + + /* We are removing the region */ + if ( rc != MPUMAP_REGION_FOUND ) + return -EINVAL; + + control_mpu_region_from_index(idx, false); + } return 0; } -- 2.25.1- Ayan
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