From: Jan Beulich <jbeulich@suse.com>
To: Penny Zheng <penny.zheng@arm.com>
Cc: Bertrand.Marquis@arm.com, Wei.Chen@arm.com, nd@arm.com,
xen-devel@lists.xenproject.org, sstabellini@kernel.org,
julien@xen.org
Subject: Re: [PATCH 05/10] xen/arm: introduce alloc_staticmem_pages
Date: Tue, 18 May 2021 09:24:13 +0200 [thread overview]
Message-ID: <a890200d-b75b-dd59-5d13-b0b211a58da5@suse.com> (raw)
In-Reply-To: <20210518052113.725808-6-penny.zheng@arm.com>
On 18.05.2021 07:21, Penny Zheng wrote:
> alloc_staticmem_pages is designated to allocate nr_pfns contiguous
> pages of static memory. And it is the equivalent of alloc_heap_pages
> for static memory.
> This commit only covers allocating at specified starting address.
>
> For each page, it shall check if the page is reserved
> (PGC_reserved) and free. It shall also do a set of necessary
> initialization, which are mostly the same ones in alloc_heap_pages,
> like, following the same cache-coherency policy and turning page
> status into PGC_state_used, etc.
>
> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
> ---
> xen/common/page_alloc.c | 64 +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 64 insertions(+)
>
> diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
> index 58b53c6ac2..adf2889e76 100644
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -1068,6 +1068,70 @@ static struct page_info *alloc_heap_pages(
> return pg;
> }
>
> +/*
> + * Allocate nr_pfns contiguous pages, starting at #start, of static memory.
> + * It is the equivalent of alloc_heap_pages for static memory
> + */
> +static struct page_info *alloc_staticmem_pages(unsigned long nr_pfns,
> + paddr_t start,
> + unsigned int memflags)
This is surely breaking the build (at this point in the series -
recall that a series should build fine at every patch boundary),
for introducing an unused static function, which most compilers
will warn about.
Also again - please avoid introducing code that's always dead for
certain architectures. Quite likely you want a Kconfig option to
put a suitable #ifdef around such functions.
And a nit: Please correct the apparently off-by-one indentation.
> +{
> + bool need_tlbflush = false;
> + uint32_t tlbflush_timestamp = 0;
> + unsigned int i;
This variable's type should (again) match nr_pfns'es (albeit I
think that parameter really wants to be nr_mfns).
> + struct page_info *pg;
> + mfn_t s_mfn;
> +
> + /* For now, it only supports allocating at specified address. */
> + s_mfn = maddr_to_mfn(start);
> + pg = mfn_to_page(s_mfn);
> + if ( !pg )
> + return NULL;
Under what conditions would mfn_to_page() return NULL?
> + for ( i = 0; i < nr_pfns; i++)
> + {
> + /*
> + * Reference count must continuously be zero for free pages
> + * of static memory(PGC_reserved).
> + */
> + ASSERT(pg[i].count_info & PGC_reserved);
> + if ( (pg[i].count_info & ~PGC_reserved) != PGC_state_free )
> + {
> + printk(XENLOG_ERR
> + "Reference count must continuously be zero for free pages"
> + "pg[%u] MFN %"PRI_mfn" c=%#lx t=%#x\n",
> + i, mfn_x(page_to_mfn(pg + i)),
> + pg[i].count_info, pg[i].tlbflush_timestamp);
Nit: Indentation again.
> + BUG();
> + }
> +
> + if ( !(memflags & MEMF_no_tlbflush) )
> + accumulate_tlbflush(&need_tlbflush, &pg[i],
> + &tlbflush_timestamp);
> +
> + /*
> + * Reserve flag PGC_reserved and change page state
DYM "Preserve ..."?
> + * to PGC_state_inuse.
> + */
> + pg[i].count_info = (pg[i].count_info & PGC_reserved) | PGC_state_inuse;
> + /* Initialise fields which have other uses for free pages. */
> + pg[i].u.inuse.type_info = 0;
> + page_set_owner(&pg[i], NULL);
> +
> + /*
> + * Ensure cache and RAM are consistent for platforms where the
> + * guest can control its own visibility of/through the cache.
> + */
> + flush_page_to_ram(mfn_x(page_to_mfn(&pg[i])),
> + !(memflags & MEMF_no_icache_flush));
> + }
> +
> + if ( need_tlbflush )
> + filtered_flush_tlb_mask(tlbflush_timestamp);
With reserved pages dedicated to a specific domain, in how far is it
possible that stale mappings from a prior use can still be around,
making such TLB flushing necessary?
Jan
next prev parent reply other threads:[~2021-05-18 7:24 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-18 5:21 [PATCH 00/10] Domain on Static Allocation Penny Zheng
2021-05-18 5:21 ` [PATCH 01/10] xen/arm: introduce domain " Penny Zheng
2021-05-18 8:58 ` Julien Grall
2021-05-19 2:22 ` Penny Zheng
2021-05-19 18:27 ` Julien Grall
2021-05-20 6:07 ` Penny Zheng
2021-05-20 8:50 ` Julien Grall
2021-06-02 10:09 ` Penny Zheng
2021-06-03 9:09 ` Julien Grall
2021-06-03 21:32 ` Stefano Stabellini
2021-06-03 22:07 ` Julien Grall
2021-06-03 23:55 ` Stefano Stabellini
2021-06-04 4:00 ` Penny Zheng
2021-06-05 2:00 ` Stefano Stabellini
2021-06-07 18:09 ` Julien Grall
2021-06-09 9:56 ` Bertrand Marquis
2021-06-09 10:47 ` Julien Grall
2021-06-15 6:08 ` Penny Zheng
2021-06-17 11:22 ` Julien Grall
2021-05-18 5:21 ` [PATCH 02/10] xen/arm: handle static memory in dt_unreserved_regions Penny Zheng
2021-05-18 9:04 ` Julien Grall
2021-05-18 5:21 ` [PATCH 03/10] xen/arm: introduce PGC_reserved Penny Zheng
2021-05-18 9:45 ` Julien Grall
2021-05-19 3:16 ` Penny Zheng
2021-05-19 9:49 ` Jan Beulich
2021-05-19 19:49 ` Julien Grall
2021-05-20 7:05 ` Jan Beulich
2021-05-19 19:46 ` Julien Grall
2021-05-20 6:19 ` Penny Zheng
2021-05-20 8:40 ` Penny Zheng
2021-05-20 8:59 ` Julien Grall
2021-05-20 9:27 ` Jan Beulich
2021-05-20 9:45 ` Julien Grall
2021-05-18 5:21 ` [PATCH 04/10] xen/arm: static memory initialization Penny Zheng
2021-05-18 7:15 ` Jan Beulich
2021-05-18 9:51 ` Penny Zheng
2021-05-18 10:43 ` Jan Beulich
2021-05-20 9:04 ` Penny Zheng
2021-05-20 9:32 ` Jan Beulich
2021-05-18 10:00 ` Julien Grall
2021-05-18 10:01 ` Julien Grall
2021-05-19 5:02 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 05/10] xen/arm: introduce alloc_staticmem_pages Penny Zheng
2021-05-18 7:24 ` Jan Beulich [this message]
2021-05-18 9:30 ` Penny Zheng
2021-05-18 10:09 ` Julien Grall
2021-05-18 10:15 ` Julien Grall
2021-05-19 5:23 ` Penny Zheng
2021-05-24 10:10 ` Penny Zheng
2021-05-24 10:24 ` Julien Grall
2021-05-18 5:21 ` [PATCH 06/10] xen: replace order with nr_pfns in assign_pages for better compatibility Penny Zheng
2021-05-18 7:27 ` Jan Beulich
2021-05-18 9:11 ` Penny Zheng
2021-05-18 10:20 ` Julien Grall
2021-05-19 5:35 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 07/10] xen/arm: intruduce alloc_domstatic_pages Penny Zheng
2021-05-18 7:34 ` Jan Beulich
2021-05-18 8:57 ` Penny Zheng
2021-05-18 11:23 ` Jan Beulich
2021-05-21 6:41 ` Penny Zheng
2021-05-21 7:09 ` Jan Beulich
2021-06-03 2:44 ` Penny Zheng
2021-05-18 12:13 ` Julien Grall
2021-05-19 7:52 ` Penny Zheng
2021-05-19 20:01 ` Julien Grall
2021-05-18 10:30 ` Julien Grall
2021-05-19 6:03 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 08/10] xen/arm: introduce reserved_page_list Penny Zheng
2021-05-18 7:39 ` Jan Beulich
2021-05-18 8:38 ` Penny Zheng
2021-05-18 11:24 ` Jan Beulich
2021-05-19 6:46 ` Penny Zheng
2021-05-18 11:02 ` Julien Grall
2021-05-19 6:43 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 09/10] xen/arm: parse `xen,static-mem` info during domain construction Penny Zheng
2021-05-18 12:09 ` Julien Grall
2021-05-19 7:58 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 10/10] xen/arm: introduce allocate_static_memory Penny Zheng
2021-05-18 12:05 ` Julien Grall
2021-05-19 7:27 ` Penny Zheng
2021-05-19 20:10 ` Julien Grall
2021-05-20 6:29 ` Penny Zheng
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