[RFC PATCH 15/31] efi_memory: add an event handler to update memory map
Ilias Apalodimas
ilias.apalodimas at linaro.org
Mon Jun 10 16:17:56 CEST 2024
Hi Sughosh
On Mon, 10 Jun 2024 at 15:25, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
>
> On Mon, 10 Jun 2024 at 17:40, Ilias Apalodimas
> <ilias.apalodimas at linaro.org> wrote:
> >
> > On Fri, 7 Jun 2024 at 21:54, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> > >
> > > There are events that would be used to notify other interested modules
> > > of any changes in available and occupied memory. This would happen
> > > when a module allocates or reserves memory, or frees up memory. These
> > > changes in memory map should be notified to other interested modules
> > > so that the allocated memory does not get overwritten. Add an event
> > > handler in the EFI memory module to update the EFI memory map
> > > accordingly when such changes happen. As a consequence, any subsequent
> > > memory request would honour the updated memory map and only available
> > > memory would be allocated from.
> >
> > So the question here, is why do we need a notifier chain overall?
> > Can't we change the EFI subsystem and allocate memory with lmb now?
> > And any special functions we have in EFI (e.g allocate aligned memory)
> > can migrate to lmb()
>
> Like we discussed offline, that was my initial attempt -- to use the
> LMB allocation API's from inside the EFI allocate pages module. But I
> was facing a lot of corner case issues, primarily in keeping the two
> memory maps the same.
I think it would worth discussing this a bit more. I like the idea of
having a single allocator more than having events to update memory
reservations
> Which is why I moved to the current
> implementation of notifying other modules, and that too only for the
> addresses in the RAM region.
The notification to 'other modules' i still done by updating the
static memory map though no?
So what corner cases we couldn't solve by having a single allocator?
Thanks
/Ilias
>
> -sughosh
>
> >
> > Cheers
> > /Ilias
> > >
> > > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > > ---
> > > lib/efi_loader/efi_memory.c | 70 ++++++++++++++++++++++++++++++-------
> > > 1 file changed, 58 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
> > > index 435e580fb3..93244161b0 100644
> > > --- a/lib/efi_loader/efi_memory.c
> > > +++ b/lib/efi_loader/efi_memory.c
> > > @@ -73,6 +73,10 @@ struct efi_pool_allocation {
> > > #if CONFIG_IS_ENABLED(MEM_MAP_UPDATE_NOTIFY)
> > > extern bool is_addr_in_ram(uintptr_t addr);
> > >
> > > +static efi_status_t __efi_add_memory_map_pg(u64 start, u64 pages,
> > > + int memory_type,
> > > + bool overlap_only_ram);
> > > +
> > > static void efi_map_update_notify(u64 addr, u64 size, u8 op)
> > > {
> > > struct event_efi_mem_map_update efi_map = {0};
> > > @@ -84,6 +88,34 @@ static void efi_map_update_notify(u64 addr, u64 size, u8 op)
> > > if (is_addr_in_ram((uintptr_t)addr))
> > > event_notify(EVT_EFI_MEM_MAP_UPDATE, &efi_map, sizeof(efi_map));
> > > }
> > > +
> > > +static int lmb_mem_map_update_sync(void *ctx, struct event *event)
> > > +{
> > > + u8 op;
> > > + u64 addr;
> > > + u64 pages;
> > > + efi_status_t status;
> > > + struct event_lmb_map_update *lmb_map = &event->data.lmb_map;
> > > +
> > > + addr = (uintptr_t)map_sysmem(lmb_map->base, 0);
> > > + pages = efi_size_in_pages(lmb_map->size + (addr & EFI_PAGE_MASK));
> > > + op = lmb_map->op;
> > > + addr &= ~EFI_PAGE_MASK;
> > > +
> > > + if (op != MAP_OP_RESERVE && op != MAP_OP_FREE) {
> > > + log_debug("Invalid map update op received (%d)\n", op);
> > > + return -1;
> > > + }
> > > +
> > > + status = __efi_add_memory_map_pg(addr, pages,
> > > + op == MAP_OP_FREE ?
> > > + EFI_CONVENTIONAL_MEMORY :
> > > + EFI_BOOT_SERVICES_DATA,
> > > + true);
> > > +
> > > + return status == EFI_SUCCESS ? 0 : -1;
> > > +}
> > > +EVENT_SPY_FULL(EVT_LMB_MAP_UPDATE, lmb_mem_map_update_sync);
> > > #endif /* MEM_MAP_UPDATE_NOTIFY */
> > >
> > > /**
> > > @@ -275,18 +307,9 @@ static s64 efi_mem_carve_out(struct efi_mem_list *map,
> > > return EFI_CARVE_LOOP_AGAIN;
> > > }
> > >
> > > -/**
> > > - * efi_add_memory_map_pg() - add pages to the memory map
> > > - *
> > > - * @start: start address, must be a multiple of EFI_PAGE_SIZE
> > > - * @pages: number of pages to add
> > > - * @memory_type: type of memory added
> > > - * @overlap_only_ram: region may only overlap RAM
> > > - * Return: status code
> > > - */
> > > -static efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
> > > - int memory_type,
> > > - bool overlap_only_ram)
> > > +static efi_status_t __efi_add_memory_map_pg(u64 start, u64 pages,
> > > + int memory_type,
> > > + bool overlap_only_ram)
> > > {
> > > struct list_head *lhandle;
> > > struct efi_mem_list *newlist;
> > > @@ -395,6 +418,29 @@ static efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
> > > }
> > > }
> > >
> > > + return EFI_SUCCESS;
> > > +}
> > > +
> > > +/**
> > > + * efi_add_memory_map_pg() - add pages to the memory map
> > > + *
> > > + * @start: start address, must be a multiple of EFI_PAGE_SIZE
> > > + * @pages: number of pages to add
> > > + * @memory_type: type of memory added
> > > + * @overlap_only_ram: region may only overlap RAM
> > > + * Return: status code
> > > + */
> > > +static efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
> > > + int memory_type,
> > > + bool overlap_only_ram)
> > > +{
> > > + efi_status_t status;
> > > +
> > > + status = __efi_add_memory_map_pg(start, pages, memory_type,
> > > + overlap_only_ram);
> > > + if (status != EFI_SUCCESS)
> > > + return status;
> > > +
> > > if (CONFIG_IS_ENABLED(MEM_MAP_UPDATE_NOTIFY))
> > > efi_map_update_notify(start, pages << EFI_PAGE_SHIFT,
> > > memory_type == EFI_CONVENTIONAL_MEMORY ?
> > > --
> > > 2.34.1
> > >
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