Re: [PATCH v2 5/8] xen/riscv: introduce asm/pmap.h header

[Julien Grall <julien@xxxxxxx>]

Hi Oleksii,

On 12/07/2024 17:22, Oleksii Kurochko wrote:
> Introduces arch_pmap_{un}map functions and select HAS_PMAP
> for CONFIG_RISCV.
>
> Additionaly it was necessary to introduce functions:
>   - mfn_to_xen_entry
>   - mfn_to_pte
>
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
> ---
> Changes in V2:
>   - newly introduced patch
> ---
>   xen/arch/riscv/Kconfig            |  1 +
>   xen/arch/riscv/include/asm/page.h |  2 ++
>   xen/arch/riscv/include/asm/pmap.h | 28 ++++++++++++++++++++++++++++
>   xen/arch/riscv/mm.c               | 14 ++++++++++++++
>   4 files changed, 45 insertions(+)
>   create mode 100644 xen/arch/riscv/include/asm/pmap.h
>
> diff --git a/xen/arch/riscv/Kconfig b/xen/arch/riscv/Kconfig
> index 259eea8d3b..0112aa8778 100644
> --- a/xen/arch/riscv/Kconfig
> +++ b/xen/arch/riscv/Kconfig
> @@ -3,6 +3,7 @@ config RISCV
>         select FUNCTION_ALIGNMENT_16B
>         select GENERIC_BUG_FRAME
>         select HAS_DEVICE_TREE
> +       select HAS_PMAP
>   
>   config RISCV_64
>         def_bool y
> diff --git a/xen/arch/riscv/include/asm/page.h 
> b/xen/arch/riscv/include/asm/page.h
> index cbbf3656d1..339074d502 100644
> --- a/xen/arch/riscv/include/asm/page.h
> +++ b/xen/arch/riscv/include/asm/page.h
> @@ -51,6 +51,8 @@ typedef struct {
>   #endif
>   } pte_t;
>   
> +pte_t mfn_to_xen_entry(mfn_t mfn, unsigned int attr);
> +
>   static inline pte_t paddr_to_pte(paddr_t paddr,
>                                    unsigned int permissions)
>   {
> diff --git a/xen/arch/riscv/include/asm/pmap.h 
> b/xen/arch/riscv/include/asm/pmap.h
> new file mode 100644
> index 0000000000..eb4c48515c
> --- /dev/null
> +++ b/xen/arch/riscv/include/asm/pmap.h
> @@ -0,0 +1,28 @@
> +#ifndef __ASM_PMAP_H__
> +#define __ASM_PMAP_H__
> +
> +#include <xen/bug.h>
> +#include <xen/mm.h>
> +
> +#include <asm/fixmap.h>
> +
> +static inline void arch_pmap_map(unsigned int slot, mfn_t mfn)
> +{
> +    pte_t *entry = &xen_fixmap[slot];
> +    pte_t pte;
> +
> +    ASSERT(!pte_is_valid(*entry));
> +
> +    pte = mfn_to_xen_entry(mfn, PAGE_HYPERVISOR_RW);
> +    pte.pte |= PTE_LEAF_DEFAULT;
> +    write_pte(entry, pte);
> +}
> +
> +static inline void arch_pmap_unmap(unsigned int slot)
> +{
> +    pte_t pte = {};
> +
> +    write_pte(&xen_fixmap[slot], pte);
> +}
> +
> +#endif /* __ASM_PMAP_H__ */
> diff --git a/xen/arch/riscv/mm.c b/xen/arch/riscv/mm.c
> index d69a174b5d..445319af08 100644
> --- a/xen/arch/riscv/mm.c
> +++ b/xen/arch/riscv/mm.c
> @@ -370,3 +370,17 @@ int map_pages_to_xen(unsigned long virt,
>       BUG_ON("unimplemented");
>       return -1;
>   }
> +
> +static inline pte_t mfn_to_pte(mfn_t mfn)
> +{
> +    unsigned long pte = mfn_x(mfn) << PTE_PPN_SHIFT;
> +    return (pte_t){ .pte = pte};
> +}
> +
> +inline pte_t mfn_to_xen_entry(mfn_t mfn, unsigned int attr)
> +{
> +    /* there is no attr field in RISC-V's pte */
> +    (void) attr;
Surely you have a way to say indicate whether an entry is readable/writable?

> +
> +    return mfn_to_pte(mfn);
> +}
Cheers,

--
Julien Grall