Re: [PATCH v3 44/52] xen/mpu: P2M initialization in MPU system

[Ayan Kumar Halder <ayankuma@xxxxxxx>]

Hi Penny,

On 26/06/2023 04:34, Penny Zheng wrote:
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>
>
> We inherit p2m_init() to do P2M initialization in MPU system, including
> VMID assignment, setting up P2M MPU region mapping table, etc.
>
> p2m_alloc_table() is responsible for allocating per-domain P2M MPU memory
> region mapping table. As a MPU memory region structure(pr_t) takes 16 bytes,
> even with maximum supported MPU memory regions, 255, MPU memory mapping table
> at most takes up less than 4KB.
>
> VSCTLR_EL2, Virtualization System Control Register, provides configuration
> information for VMSAv8-64 and PMSAv8-64 virtualization using stage 2
> of EL1&0 translation regime, bit[63:48] of which determines VMID for the
> EL1-Guest-OS.
>
> Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
> v3:
> - new commit
> ---
>   xen/arch/arm/include/asm/mpu/mm.h |  3 ++
>   xen/arch/arm/include/asm/p2m.h    |  5 +++
>   xen/arch/arm/mpu/mm.c             | 22 ++++++++++
>   xen/arch/arm/mpu/p2m.c            | 69 +++++++++++++++++++++++++++++++
>   4 files changed, 99 insertions(+)
>
> diff --git a/xen/arch/arm/include/asm/mpu/mm.h 
> b/xen/arch/arm/include/asm/mpu/mm.h
> index a83519ad13..4df69245c6 100644
> --- a/xen/arch/arm/include/asm/mpu/mm.h
> +++ b/xen/arch/arm/include/asm/mpu/mm.h
> @@ -2,6 +2,8 @@
>   #ifndef __ARCH_ARM_MM_MPU__
>   #define __ARCH_ARM_MM_MPU__
#ifdef CONFIG_ARM_64
> +#include <asm/arm64/mpu.h>
#endif
> +
>   extern struct page_info *frame_table;
>   extern unsigned long frametable_pdx_end;
>
> @@ -11,6 +13,7 @@ extern uint8_t is_mm_range_mapped(paddr_t pa, paddr_t len);
>   extern void *map_mm_range(paddr_t pa, size_t len, unsigned int attributes);
>   extern void unmap_mm_range(paddr_t pa);
>   extern bool is_mm_range_mapped_transient(paddr_t pa, paddr_t len);
> +extern pr_t *alloc_mpumap(void);
>
>   #endif /* __ARCH_ARM_MM_MPU__ */
>
> diff --git a/xen/arch/arm/include/asm/p2m.h b/xen/arch/arm/include/asm/p2m.h
> index d9c91d4a98..c3598d514e 100644
> --- a/xen/arch/arm/include/asm/p2m.h
> +++ b/xen/arch/arm/include/asm/p2m.h
> @@ -61,8 +61,13 @@ struct p2m_domain {
>       /* Current VMID in use */
>       uint16_t vmid;
>
> +#ifndef CONFIG_HAS_MPU
>       /* Current Translation Table Base Register for the p2m */
>       uint64_t vttbr;
> +#else
> +    /* Current Virtualization System Control Register for the p2m */
> +    uint64_t vsctlr;
register_t vsctlr;

So that it is 64-bit for ARM_64 and 32-bit for ARM_32.

> +#endif
>
>       /* Highest guest frame that's ever been mapped in the p2m */
>       gfn_t max_mapped_gfn;
> diff --git a/xen/arch/arm/mpu/mm.c b/xen/arch/arm/mpu/mm.c
> index 27d924e449..de5da96b80 100644
> --- a/xen/arch/arm/mpu/mm.c
> +++ b/xen/arch/arm/mpu/mm.c
> @@ -872,6 +872,28 @@ void __init remove_early_mappings(paddr_t dtb_paddr)
>               panic("Unable to destroy early Device-Tree mapping.\n");
>   }
>
> +/*
> + * Standard entry to dynamically allocate MPU memory region mapping table.
> + * A 4KB page is enough for holding the maximum supported MPU memory
> + * regions.
> + */
> +pr_t *alloc_mpumap(void)
> +{
> +    pr_t *map;
> +
> +    /*
> +     * A MPU memory region structure(pr_t) takes 16 bytes, even with maximum
> +     * supported MPU memory regions, 255, MPU memory mapping table at most
> +     * takes up less than 4KB.
> +     */
> +    map = alloc_xenheap_pages(0, 0);
> +    if ( map == NULL )
> +        return NULL;
> +
> +    clear_page(map);
> +    return map;
> +}
> +
>   /*
>    * Local variables:
>    * mode: C
> diff --git a/xen/arch/arm/mpu/p2m.c b/xen/arch/arm/mpu/p2m.c
> index a7a3912a9a..8f728f8957 100644
> --- a/xen/arch/arm/mpu/p2m.c
> +++ b/xen/arch/arm/mpu/p2m.c
> @@ -4,6 +4,7 @@
>   #include <xen/sched.h>
>   #include <xen/warning.h>
>
> +#include <asm/mpu/mm.h>
>   #include <asm/p2m.h>
>   #include <asm/processor.h>
>   #include <asm/sysregs.h>
> @@ -97,6 +98,74 @@ fault:
>       panic("Hardware with no PMSAv8-64 support in any translation regime.\n");
>   }
>
> +static uint64_t __init generate_vsctlr(uint16_t vmid)
> +{
> +    return ((uint64_t)vmid << 48);
> +}
Please move ^^^ to ./xen/arch/arm/include/asm/arm64/mpu.h as it differs 
between R82 and R52
- Ayan

> +
> +static int __init p2m_alloc_table(struct domain *d)
> +{
> +    struct p2m_domain *p2m = p2m_get_hostp2m(d);
> +    pr_t* p2m_map;
> +
> +    p2m_map = alloc_mpumap();
> +    if ( !p2m_map )
> +    {
> +        printk(XENLOG_G_ERR "DOM%pd: p2m: unable to allocate P2M MPU mapping 
> table\n", d);
> +        return -ENOMEM;
> +    }
> +
> +    p2m->root = virt_to_page((const void *)p2m_map);
> +
> +    return 0;
> +}
> +
> +int p2m_init(struct domain *d)
> +{
> +    struct p2m_domain *p2m = p2m_get_hostp2m(d);
> +    int rc = 0;
> +    unsigned int cpu;
> +
> +    rwlock_init(&p2m->lock);
> +    spin_lock_init(&d->arch.paging.lock);
> +
> +    p2m->vmid = INVALID_VMID;
> +    p2m->max_mapped_gfn = _gfn(0);
> +    p2m->lowest_mapped_gfn = _gfn(ULONG_MAX);
> +
> +    p2m->default_access = p2m_access_rwx;
> +    /* mem_access is NOT supported in MPU system. */
> +    p2m->mem_access_enabled = false;
> +
> +    /*
> +     * Make sure that the type chosen to is able to store an vCPU ID
> +     * between 0 and the maximum of virtual CPUS supported as long as
> +     * the INVALID_VCPU_ID.
> +     */
> +    BUILD_BUG_ON((1 << (sizeof(p2m->last_vcpu_ran[0]) * 8)) < MAX_VIRT_CPUS);
> +    BUILD_BUG_ON((1 << (sizeof(p2m->last_vcpu_ran[0]) * 8)) < INVALID_VCPU_ID);
> +
> +    for_each_possible_cpu(cpu)
> +       p2m->last_vcpu_ran[cpu] = INVALID_VCPU_ID;
> +
> +    /*
> +     * "Trivial" initialisation is now complete.  Set the backpointer so
> +     * p2m_teardown() and friends know to do something.
> +     */
> +    p2m->domain = d;
> +
> +    rc = p2m_alloc_vmid(d);
> +    if ( rc )
> +        return rc;
> +    p2m->vsctlr = generate_vsctlr(p2m->vmid);
> +
> +    rc = p2m_alloc_table(d);
> +    if ( rc )
> +        return rc;
> +
> +    return rc;
> +}
> +
>   /*
>    * Local variables:
>    * mode: C
> --
> 2.25.1