Hi Luca,
On 23/04/2024 10:25, Luca Fancellu wrote:
>
>
> From: Penny Zheng <[email protected]>
>
> We are doing foreign memory mapping for static shared memory, and
> there is a great possibility that it could be super mapped.
> But today, p2m_put_l3_page could not handle superpages.
>
> This commits implements a new function p2m_put_superpage to handle superpages,
> specifically for helping put extra references for foreign superpages.
>
> Signed-off-by: Penny Zheng <[email protected]>
> Signed-off-by: Luca Fancellu <[email protected]>
> ---
> v1:
> - patch from
> https://patchwork.kernel.org/project/xen-devel/patch/[email protected]/
> ---
> xen/arch/arm/mmu/p2m.c | 58 +++++++++++++++++++++++++++++++-----------
> 1 file changed, 43 insertions(+), 15 deletions(-)
>
> diff --git a/xen/arch/arm/mmu/p2m.c b/xen/arch/arm/mmu/p2m.c
> index 41fcca011cf4..479a80fbd4cf 100644
> --- a/xen/arch/arm/mmu/p2m.c
> +++ b/xen/arch/arm/mmu/p2m.c
> @@ -753,17 +753,9 @@ static int p2m_mem_access_radix_set(struct p2m_domain
> *p2m, gfn_t gfn,
> return rc;
> }
>
> -/*
> - * Put any references on the single 4K page referenced by pte.
> - * TODO: Handle superpages, for now we only take special references for leaf
> - * pages (specifically foreign ones, which can't be super mapped today).
> - */
> -static void p2m_put_l3_page(const lpae_t pte)
> +/* Put any references on the single 4K page referenced by mfn. */
> +static void p2m_put_l3_page(mfn_t mfn, unsigned type)
Shouldn't type be of p2m_type_t?
> {
> - mfn_t mfn = lpae_get_mfn(pte);
> -
> - ASSERT(p2m_is_valid(pte));
> -
> /*
> * TODO: Handle other p2m types
> *
> @@ -771,16 +763,53 @@ static void p2m_put_l3_page(const lpae_t pte)
> * flush the TLBs if the page is reallocated before the end of
> * this loop.
> */
> - if ( p2m_is_foreign(pte.p2m.type) )
> + if ( p2m_is_foreign(type) )
> {
> ASSERT(mfn_valid(mfn));
> put_page(mfn_to_page(mfn));
> }
> /* Detect the xenheap page and mark the stored GFN as invalid. */
> - else if ( p2m_is_ram(pte.p2m.type) && is_xen_heap_mfn(mfn) )
> + else if ( p2m_is_ram(type) && is_xen_heap_mfn(mfn) )
> page_set_xenheap_gfn(mfn_to_page(mfn), INVALID_GFN);
> }
>
> +/* Put any references on the superpage referenced by mfn. */
> +static void p2m_put_superpage(mfn_t mfn, unsigned int next_level, unsigned
> type)
Shouldn't type be of p2m_type_t?
> +{
> + unsigned int i;
> + unsigned int level_order = XEN_PT_LEVEL_ORDER(next_level);
> +
> + for ( i = 0; i < XEN_PT_LPAE_ENTRIES; i++ )
> + {
> + if ( next_level == 3 )
> + p2m_put_l3_page(mfn, type);
> + else
> + p2m_put_superpage(mfn, next_level + 1, type);
> +
> + mfn = mfn_add(mfn, 1 << level_order);
> + }
> +}
> +
> +/* Put any references on the page referenced by pte. */
> +static void p2m_put_page(const lpae_t pte, unsigned int level)
> +{
> + mfn_t mfn = lpae_get_mfn(pte);
> +
> + ASSERT(p2m_is_valid(pte));
> +
> + /*
> + * We are either having a first level 1G superpage or a
> + * second level 2M superpage.
> + */
> + if ( p2m_is_superpage(pte, level) )
> + return p2m_put_superpage(mfn, level + 1, pte.p2m.type);
> + else
No need for this else
> + {
> + ASSERT(level == 3);
> + return p2m_put_l3_page(mfn, pte.p2m.type);
> + }
> +}
> +
> /* Free lpae sub-tree behind an entry */
> static void p2m_free_entry(struct p2m_domain *p2m,
> lpae_t entry, unsigned int level)
> @@ -809,9 +838,8 @@ static void p2m_free_entry(struct p2m_domain *p2m,
> #endif
>
> p2m->stats.mappings[level]--;
> - /* Nothing to do if the entry is a super-page. */
> - if ( level == 3 )
> - p2m_put_l3_page(entry);
> + p2m_put_page(entry, level);
> +
> return;
> }
>
> --
> 2.34.1
>
~Michal
