Re: [PATCH v2 12/14] arm64: realm: Support nonsecure ITS emulation shared

Catalin Marinas
2024-05-15T11:01:07Z

On Fri, Apr 12, 2024 at 09:42:11AM +0100, Steven Price wrote:
> @@ -198,6 +201,33 @@ static DEFINE_IDA(its_vpeid_ida);
> #define gic_data_rdist_rd_base() (gic_data_rdist()->rd_base)
> #define gic_data_rdist_vlpi_base() (gic_data_rdist_rd_base() + SZ_128K)
>
> +static struct page *its_alloc_shared_pages_node(int node, gfp_t gfp,
> + unsigned int order)
> +{
> + struct page *page;
> +
> + if (node == NUMA_NO_NODE)
> + page = alloc_pages(gfp, order);
> + else
> + page = alloc_pages_node(node, gfp, order);

I think you can just call alloc_pages_node() in both cases. This
function takes care of the NUMA_NO_NODE case itself.

> +
> + if (page)
> + set_memory_decrypted((unsigned long)page_address(page),
> + 1 << order);
> + return page;
> +}
> +
> +static struct page *its_alloc_shared_pages(gfp_t gfp, unsigned int order)
> +{
> + return its_alloc_shared_pages_node(NUMA_NO_NODE, gfp, order);
> +}
> +
> +static void its_free_shared_pages(void *addr, unsigned int order)
> +{
> + set_memory_encrypted((unsigned long)addr, 1 << order);
> + free_pages((unsigned long)addr, order);
> +}

More of a nitpick on the naming: Are these functions used by the host as
well? The 'shared' part of the name does not make much sense, so maybe
just call them its_alloc_page() etc.

> @@ -3432,7 +3468,16 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
> nr_ites = max(2, nvecs);
> sz = nr_ites * (FIELD_GET(GITS_TYPER_ITT_ENTRY_SIZE, its->typer) + 1);
> sz = max(sz, ITS_ITT_ALIGN) + ITS_ITT_ALIGN - 1;
> - itt = kzalloc_node(sz, GFP_KERNEL, its->numa_node);
> + itt_order = get_order(sz);
> + page = its_alloc_shared_pages_node(its->numa_node,
> + GFP_KERNEL | __GFP_ZERO,
> + itt_order);

How much do we waste by going for a full page always if this is going to
be used on the host?

> + if (!page)
> + return NULL;
> + itt = (void *)page_address(page);

page_address() has the void * type already.

--
Catalin