Hi Julien
> -----Original Message-----
> From: Julien Grall <jul...@xen.org>
> Sent: Tuesday, May 18, 2021 6:01 PM
> To: Penny Zheng <penny.zh...@arm.com>; xen-devel@lists.xenproject.org;
> sstabell...@kernel.org
> Cc: Bertrand Marquis <bertrand.marq...@arm.com>; Wei Chen
> <wei.c...@arm.com>; nd <n...@arm.com>
> Subject: Re: [PATCH 04/10] xen/arm: static memory initialization
>
> Hi Penny,
>
> On 18/05/2021 06:21, Penny Zheng wrote:
> > This patch introduces static memory initialization, during system RAM boot
> up.
> >
> > New func init_staticmem_pages is the equivalent of init_heap_pages,
> > responsible for static memory initialization.
> >
> > Helper func free_staticmem_pages is the equivalent of free_heap_pages,
> > to free nr_pfns pages of static memory.
> > For each page, it includes the following steps:
> > 1. change page state from in-use(also initialization state) to free
> > state and grant PGC_reserved.
> > 2. set its owner NULL and make sure this page is not a guest frame any
> > more 3. follow the same cache coherency policy in free_heap_pages 4.
> > scrub the page in need
> >
> > Signed-off-by: Penny Zheng <penny.zh...@arm.com>
> > ---
> > xen/arch/arm/setup.c | 2 ++
> > xen/common/page_alloc.c | 70
> +++++++++++++++++++++++++++++++++++++++++
> > xen/include/xen/mm.h | 3 ++
> > 3 files changed, 75 insertions(+)
> >
> > diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c index
> > 444dbbd676..f80162c478 100644
> > --- a/xen/arch/arm/setup.c
> > +++ b/xen/arch/arm/setup.c
> > @@ -818,6 +818,8 @@ static void __init setup_mm(void)
> >
> > setup_frametable_mappings(ram_start, ram_end);
> > max_page = PFN_DOWN(ram_end);
> > +
> > + init_staticmem_pages();
> > }
> > #endif
> >
> > diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c index
> > ace6333c18..58b53c6ac2 100644
> > --- a/xen/common/page_alloc.c
> > +++ b/xen/common/page_alloc.c
> > @@ -150,6 +150,9 @@
> > #define p2m_pod_offline_or_broken_hit(pg) 0
> > #define p2m_pod_offline_or_broken_replace(pg) BUG_ON(pg != NULL)
> > #endif
> > +#ifdef CONFIG_ARM_64
> > +#include <asm/setup.h>
> > +#endif
> >
> > /*
> > * Comma-separated list of hexadecimal page numbers containing bad
> bytes.
> > @@ -1512,6 +1515,49 @@ static void free_heap_pages(
> > spin_unlock(&heap_lock);
> > }
> >
> > +/* Equivalent of free_heap_pages to free nr_pfns pages of static
> > +memory. */ static void free_staticmem_pages(struct page_info *pg,
> > +unsigned long nr_pfns,
>
> This function is dealing with MFNs, so the second parameter should be called
> nr_mfns.
>
Agreed, thx.
> > + bool need_scrub) {
> > + mfn_t mfn = page_to_mfn(pg);
> > + int i;
> > +
> > + for ( i = 0; i < nr_pfns; i++ )
> > + {
> > + switch ( pg[i].count_info & PGC_state )
> > + {
> > + case PGC_state_inuse:
> > + BUG_ON(pg[i].count_info & PGC_broken);
> > + /* Make it free and reserved. */
> > + pg[i].count_info = PGC_state_free | PGC_reserved;
> > + break;
> > +
> > + default:
> > + printk(XENLOG_ERR
> > + "Page state shall be only in PGC_state_inuse. "
> > + "pg[%u] MFN %"PRI_mfn" count_info=%#lx
> tlbflush_timestamp=%#x.\n",
> > + i, mfn_x(mfn) + i,
> > + pg[i].count_info,
> > + pg[i].tlbflush_timestamp);
> > + BUG();
> > + }
> > +
> > + /*
> > + * Follow the same cache coherence scheme in free_heap_pages.
> > + * If a page has no owner it will need no safety TLB flush.
> > + */
> > + pg[i].u.free.need_tlbflush = (page_get_owner(&pg[i]) != NULL);
> > + if ( pg[i].u.free.need_tlbflush )
> > + page_set_tlbflush_timestamp(&pg[i]);
> > +
> > + /* This page is not a guest frame any more. */
> > + page_set_owner(&pg[i], NULL);
> > + set_gpfn_from_mfn(mfn_x(mfn) + i, INVALID_M2P_ENTRY);
>
> The code looks quite similar to free_heap_pages(). Could we possibly create
> an helper which can be called from both?
>
Ok, I will extract the common code here and there.
> > +
> > + if ( need_scrub )
> > + scrub_one_page(&pg[i]);
>
> So the scrubbing will be synchronous. Is it what we want?
>
> You also seem to miss the flush the call to flush_page_to_ram().
>
Yeah, right now, it is synchronous.
I guess that it is not an optimal choice, only a workable one right now.
I'm trying to borrow some asynchronous scrubbing ideas from heap in the future.
Yes! If we are doing synchronous scrubbing, we need to flush_page_to_ram(). Thx.
> > + }
> > +}
> >
> > /*
> > * Following rules applied for page offline:
> > @@ -1828,6 +1874,30 @@ static void init_heap_pages(
> > }
> > }
> >
> > +/* Equivalent of init_heap_pages to do static memory initialization
> > +*/ void __init init_staticmem_pages(void) {
> > + int bank;
> > +
> > + /*
> > + * TODO: Considering NUMA-support scenario.
> > + */
> > + for ( bank = 0 ; bank < bootinfo.static_mem.nr_banks; bank++ )
>
> bootinfo is arm specific, so this code should live in arch/arm rather than
> common/.
>
Yes, I'm considering to create a new CONFIG_STATIC_MEM to include all
static-memory-related functions.
> > + {
> > + paddr_t bank_start = bootinfo.static_mem.bank[bank].start;
> > + paddr_t bank_size = bootinfo.static_mem.bank[bank].size;
> > + paddr_t bank_end = bank_start + bank_size;
> > +
> > + bank_start = round_pgup(bank_start);
> > + bank_end = round_pgdown(bank_end);
> > + if ( bank_end <= bank_start )
> > + return;
> > +
> > + free_staticmem_pages(maddr_to_page(bank_start),
> > + (bank_end - bank_start) >> PAGE_SHIFT, false);
> > + }
> > +}
> > +
> > static unsigned long avail_heap_pages(
> > unsigned int zone_lo, unsigned int zone_hi, unsigned int node)
> > {
> > diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h index
> > 667f9dac83..8b1a2207b2 100644
> > --- a/xen/include/xen/mm.h
> > +++ b/xen/include/xen/mm.h
> > @@ -85,6 +85,9 @@ bool scrub_free_pages(void);
> > } while ( false )
> > #define FREE_XENHEAP_PAGE(p) FREE_XENHEAP_PAGES(p, 0)
> >
> > +/* Static Memory */
> > +void init_staticmem_pages(void);
> > +
> > /* Map machine page range in Xen virtual address space. */
> > int map_pages_to_xen(
> > unsigned long virt,
> >
>
> Cheers,
>
> --
> Julien Grall
Cheers
Penny
