Re: [PATCH v2 36/39] xen/riscv: add minimal stuff to asm/mm.h to build full Xen

[Jan Beulich <jbeulich@xxxxxxxx>]

On 24.11.2023 11:30, Oleksii Kurochko wrote:
> --- a/xen/arch/riscv/include/asm/mm.h
> +++ b/xen/arch/riscv/include/asm/mm.h
> @@ -3,10 +3,271 @@
>  #ifndef _ASM_RISCV_MM_H
>  #define _ASM_RISCV_MM_H
>  
> +#include <public/xen.h>
> +#include <xen/pdx.h>
> +#include <xen/types.h>
> +
> +#include <asm/page.h>
>  #include <asm/page-bits.h>
>  
> -#define pfn_to_paddr(pfn) ((paddr_t)(pfn) << PAGE_SHIFT)
> -#define paddr_to_pfn(pa)  ((unsigned long)((pa) >> PAGE_SHIFT))

I'm a little puzzled here: Just a few patches ago you introduced them into
asm/page.h, and (only) now you're removing them here.

> +#define paddr_to_pdx(pa)    mfn_to_pdx(maddr_to_mfn(pa))
> +#define gfn_to_gaddr(gfn)   pfn_to_paddr(gfn_x(gfn))
> +#define gaddr_to_gfn(ga)    _gfn(paddr_to_pfn(ga))
> +#define mfn_to_maddr(mfn)   pfn_to_paddr(mfn_x(mfn))
> +#define maddr_to_mfn(ma)    _mfn(paddr_to_pfn(ma))
> +#define vmap_to_mfn(va)     maddr_to_mfn(virt_to_maddr((vaddr_t)va))
> +#define vmap_to_page(va)    mfn_to_page(vmap_to_mfn(va))
> +#define paddr_to_pdx(pa)    mfn_to_pdx(maddr_to_mfn(pa))
> +#define gfn_to_gaddr(gfn)   pfn_to_paddr(gfn_x(gfn))
> +#define gaddr_to_gfn(ga)    _gfn(paddr_to_pfn(ga))
> +#define mfn_to_maddr(mfn)   pfn_to_paddr(mfn_x(mfn))
> +#define maddr_to_mfn(ma)    _mfn(paddr_to_pfn(ma))
> +#define vmap_to_mfn(va)     maddr_to_mfn(virt_to_maddr((vaddr_t)va))
> +#define vmap_to_page(va)    mfn_to_page(vmap_to_mfn(va))
> +
> +#define virt_to_maddr(va) ((paddr_t)((vaddr_t)(va) & PADDR_MASK))
> +#define maddr_to_virt(pa) ((void *)((paddr_t)(pa) | XEN_VIRT_START))

Is this really XEN_VIRT_START? I.e. does your directmap start there,
right where the Xen image area also starts?

> +/* Convert between Xen-heap virtual addresses and machine frame numbers. */
> +#define __virt_to_mfn(va) (virt_to_maddr(va) >> PAGE_SHIFT)
> +#define __mfn_to_virt(mfn) (maddr_to_virt((paddr_t)(mfn) << PAGE_SHIFT))

Nit: Excess parentheses again.

> +/* Convert between Xen-heap virtual addresses and page-info structures. */
> +static inline struct page_info *virt_to_page(const void *v)
> +{
> +    BUG();
> +    return NULL;
> +}
> +
> +/*
> + * We define non-underscored wrappers for above conversion functions.
> + * These are overriden in various source files while underscored version
> + * remain intact.
> + */
> +#define virt_to_mfn(va)     __virt_to_mfn(va)
> +#define mfn_to_virt(mfn)    __mfn_to_virt(mfn)
> +
> +struct page_info
> +{
> +    /* Each frame can be threaded onto a doubly-linked list. */
> +    struct page_list_entry list;
> +
> +    /* Reference count and various PGC_xxx flags and fields. */
> +    unsigned long count_info;
> +
> +    /* Context-dependent fields follow... */
> +    union {
> +        /* Page is in use: ((count_info & PGC_count_mask) != 0). */
> +        struct {
> +            /* Type reference count and various PGT_xxx flags and fields. */
> +            unsigned long type_info;
> +        } inuse;
> +        /* Page is on a free list: ((count_info & PGC_count_mask) == 0). */
> +        union {
> +            struct {
> +                /*
> +                 * Index of the first *possibly* unscrubbed page in the 
> buddy.
> +                 * One more bit than maximum possible order to accommodate
> +                 * INVALID_DIRTY_IDX.
> +                 */
> +#define INVALID_DIRTY_IDX ((1UL << (MAX_ORDER + 1)) - 1)
> +                unsigned long first_dirty:MAX_ORDER + 1;
> +
> +                /* Do TLBs need flushing for safety before next page use? */
> +                bool need_tlbflush:1;
> +
> +#define BUDDY_NOT_SCRUBBING    0
> +#define BUDDY_SCRUBBING        1
> +#define BUDDY_SCRUB_ABORT      2
> +                unsigned long scrub_state:2;
> +            };
> +
> +            unsigned long val;
> +            } free;

Something's wrong with indentation here.

> +    } u;
> +
> +    union {
> +        /* Page is in use, but not as a shadow. */
> +        struct {
> +            /* Owner of this page (zero if page is anonymous). */
> +            struct domain *domain;
> +        } inuse;
> +
> +        /* Page is on a free list. */
> +        struct {
> +            /* Order-size of the free chunk this page is the head of. */
> +            unsigned int order;
> +        } free;
> +
> +    } v;
> +
> +    union {
> +        /*
> +         * Timestamp from 'TLB clock', used to avoid extra safety flushes.
> +         * Only valid for: a) free pages, and b) pages with zero type count
> +         */
> +        u32 tlbflush_timestamp;

Nit: uint32_t and ...

> +    };
> +    u64 pad;

... uint64_t please in new code. Assuming, for the latter, you really need
the field in the first place: I can't see what it's needed for.

> +};
> +
> +#define frame_table ((struct page_info *)FRAMETABLE_VIRT_START)
> +
> +/* PDX of the first page in the frame table. */
> +extern unsigned long frametable_base_pdx;
> +
> +/* Convert between machine frame numbers and page-info structures. */
> +#define mfn_to_page(mfn)                                            \
> +    (frame_table + (mfn_to_pdx(mfn) - frametable_base_pdx))
> +#define page_to_mfn(pg)                                             \
> +    pdx_to_mfn((unsigned long)((pg) - frame_table) + frametable_base_pdx)
> +
> +static inline void *page_to_virt(const struct page_info *pg)
> +{
> +    return mfn_to_virt(mfn_x(page_to_mfn(pg)));
> +}
> +
> +/*
> + * Common code requires get_page_type and put_page_type.
> + * We don't care about typecounts so we just do the minimum to make it
> + * happy.
> + */
> +static inline int get_page_type(struct page_info *page, unsigned long type)
> +{
> +    return 1;
> +}
> +
> +static inline void put_page_type(struct page_info *page)
> +{
> +    return;

No need for this; the body can ve entirely empty, as we have it elsewhere.

> +}
> +
> +/* TODO */
> +static inline bool get_page_nr(struct page_info *page, const struct domain 
> *domain,
> +                        unsigned long nr)
> +{
> +    BUG();
> +}
> +static inline void put_page_nr(struct page_info *page, unsigned long nr)
> +{
> +    BUG();
> +}

What are these two needed for?

> +static inline void put_page_and_type(struct page_info *page)
> +{
> +    put_page_type(page);
> +    put_page(page);
> +}
> +
> +/*
> + * RISCV does not have an M2P, but common code expects a handful of
> + * M2P-related defines and functions. Provide dummy versions of these.
> + */
> +#define INVALID_M2P_ENTRY        (~0UL)
> +#define SHARED_M2P_ENTRY         (~0UL - 1UL)
> +#define SHARED_M2P(_e)           ((_e) == SHARED_M2P_ENTRY)
> +
> +/* Xen always owns P2M on PPC */

PPC?

> +#define set_gpfn_from_mfn(mfn, pfn) do { (void) (mfn), (void)(pfn); } while 
> (0)
> +#define mfn_to_gfn(d, mfn) ((void)(d), _gfn(mfn_x(mfn)))
> +
> +#define PDX_GROUP_SHIFT (16 + 5)
> +
> +static inline unsigned long domain_get_maximum_gpfn(struct domain *d)
> +{
> +    BUG();
> +    return 0;
> +}
> +
> +static inline long arch_memory_op(int op, XEN_GUEST_HANDLE_PARAM(void) arg)
> +{
> +    BUG();
> +    return 0;
> +}
> +
> +/*
> + * On RISCV, all the RAM is currently direct mapped in Xen.
> + * Hence return always true.
> + */
> +static inline bool arch_mfns_in_directmap(unsigned long mfn, unsigned long 
> nr)
> +{
> +    return true;
> +}
> +
> +#define PG_shift(idx)   (BITS_PER_LONG - (idx))
> +#define PG_mask(x, idx) (x ## UL << PG_shift(idx))
> +
> +#define PGT_none          PG_mask(0, 1)  /* no special uses of this page   */
> +#define PGT_writable_page PG_mask(1, 1)  /* has writable mappings?         */
> +#define PGT_type_mask     PG_mask(1, 1)  /* Bits 31 or 63.                 */
> +
> + /* Count of uses of this frame as its current type. */
> +#define PGT_count_width   PG_shift(2)
> +#define PGT_count_mask    ((1UL<<PGT_count_width)-1)
> +
> +/*
> + * Page needs to be scrubbed. Since this bit can only be set on a page that 
> is
> + * free (i.e. in PGC_state_free) we can reuse PGC_allocated bit.
> + */
> +#define _PGC_need_scrub   _PGC_allocated
> +#define PGC_need_scrub    PGC_allocated
> +
> +//  /* Cleared when the owning guest 'frees' this page. */
> +#define _PGC_allocated    PG_shift(1)
> +#define PGC_allocated     PG_mask(1, 1)
> +  /* Page is Xen heap? */
> +#define _PGC_xen_heap     PG_shift(2)
> +#define PGC_xen_heap      PG_mask(1, 2)
> +#ifdef CONFIG_STATIC_MEMORY
> +/* Page is static memory */
> +#define _PGC_static    PG_shift(3)
> +#define PGC_static     PG_mask(1, 3)
> +#else
> +#define PGC_static     0
> +#endif

Please omit this until you really know whether you're going to support
static memory.

> +/* ... */

???

> +/* Page is broken? */
> +#define _PGC_broken       PG_shift(7)
> +#define PGC_broken        PG_mask(1, 7)
> + /* Mutually-exclusive page states: { inuse, offlining, offlined, free }. */
> +#define PGC_state         PG_mask(3, 9)
> +#define PGC_state_inuse   PG_mask(0, 9)
> +#define PGC_state_offlining PG_mask(1, 9)
> +#define PGC_state_offlined PG_mask(2, 9)
> +#define PGC_state_free    PG_mask(3, 9)
> +// #define page_state_is(pg, st) (((pg)->count_info&PGC_state) == 
> PGC_state_##st)
> +
> +/* Count of references to this frame. */
> +#define PGC_count_width   PG_shift(9)
> +#define PGC_count_mask    ((1UL<<PGC_count_width)-1)
> +
> +#define page_state_is(pg, st) (((pg)->count_info&PGC_state) == 
> PGC_state_##st)
> +
> +#define _PGC_extra        PG_shift(10)
> +#define PGC_extra         PG_mask(1, 10)
> +
> +#define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap)
> +#define is_xen_heap_mfn(mfn) \
> +    (mfn_valid(mfn) && is_xen_heap_page(mfn_to_page(mfn)))
> +
> +#define is_xen_fixed_mfn(mfn)                                   \
> +    ((mfn_to_maddr(mfn) >= virt_to_maddr(&_start)) &&           \
> +     (mfn_to_maddr(mfn) <= virt_to_maddr((vaddr_t)_end - 1)))
> +
> +#define page_get_owner(_p)    (_p)->v.inuse.domain
> +#define page_set_owner(_p,_d) ((_p)->v.inuse.domain = (_d))
> +
> +/* TODO: implement */
> +#define mfn_valid(mfn) ({ (void) (mfn); 0; })
> +// #define max_page (0UL)

???

> +#define mfn_to_gfn(d, mfn) ((void)(d), _gfn(mfn_x(mfn)))
> +
> +#define domain_set_alloc_bitsize(d) ((void)0)
> +#define domain_clamp_alloc_bitsize(d, b) (b)
> +
> +#define PFN_ORDER(_pfn) ((_pfn)->v.free.order)

No leading underscore needed here, I suppose.

Jan