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Re: [PATCH V4 10/10] xen/arm: introduce allocate_static_memory
Hi Penny,
On 28/07/2021 11:27, Penny Zheng wrote:
This commit introduces allocate_static_memory to allocate static memory as
guest RAM for Domain on Static Allocation.
It uses acquire_domstatic_pages to acquire pre-configured static memory
for this domain, and uses guest_physmap_add_page to set up P2M table.
These pre-defined static memory banks shall be firstly mapped to the
fixed guest RAM address `GUEST_RAM0_BASE`. And until it exhausts the
`GUEST_RAM0_SIZE`, it will seek to `GUEST_RAM1_BASE`, and so on.
`GUEST_RAM0` may take up several pre-defined physical RAM regions.
Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>
---
xen/arch/arm/domain_build.c | 137 +++++++++++++++++++++++++++++++++++-
1 file changed, 135 insertions(+), 2 deletions(-)
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index cdb16f2086..ed290ee31b 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -480,6 +480,139 @@ fail:
(unsigned long)kinfo->unassigned_mem >> 10);
}
+static bool __init append_static_memory_to_bank(struct domain *d,
+ struct membank *bank,
+ mfn_t smfn,
+ paddr_t size)
+{
+ int res;
+ paddr_t tot_size = size;
+ /* Infer next GFN. */
+ gfn_t sgfn = gaddr_to_gfn(bank->start + bank->size);
+
+ while ( tot_size > 0 )
+ {
+ unsigned int order = get_allocation_size(tot_size);
+
+ res = guest_physmap_add_page(d, sgfn, smfn, order);
+ if ( res )
+ {
+ dprintk(XENLOG_ERR, "Failed map pages to DOMU: %d", res);
+ return false;
+ }
+
+ smfn = mfn_add(smfn, 1UL << order);
+ tot_size -= (1UL << (PAGE_SHIFT + order));
+ }
AFAICT, the loop is only here to suit guest_physmap_add_page(). Further
down the line, the order will be converted back to a number of pages
before calling p2m_insert_mapping().
So how about exporting p2m_insert_mapping() and use it?
+ > + bank->size = bank->size + size;
We usually add a newline before the last return of the function.
+ return true;
+}
+
+/* Allocate memory from static memory as RAM for one specific domain d. */
+static void __init allocate_static_memory(struct domain *d,
+ struct kernel_info *kinfo,
+ const struct dt_property *prop,
+ u32 addr_cells, u32 size_cells)
+{
+ unsigned int nr_banks, gbank, bank = 0;
+ const uint64_t rambase[] = GUEST_RAM_BANK_BASES;
+ const uint64_t ramsize[] = GUEST_RAM_BANK_SIZES;
+ const __be32 *cell;
+ u32 reg_cells = addr_cells + size_cells;
+ u64 tot_size = 0;
+ paddr_t pbase, psize, gsize;
+ mfn_t smfn;
+
+ /* Start with GUEST_RAM0. */
+ kinfo->mem.nr_banks = 0;
+ gbank = 0;
+ gsize = ramsize[gbank];
+ kinfo->mem.bank[gbank].start = rambase[gbank];
+
+ cell = (const __be32 *)prop->value;
+ nr_banks = (prop->length) / (reg_cells * sizeof (u32));
+ BUG_ON(nr_banks > NR_MEM_BANKS);
+
+ while ( bank < nr_banks )
+ {
+ device_tree_get_reg(&cell, addr_cells, size_cells, &pbase, &psize);
+ tot_size += psize;
+ smfn = maddr_to_mfn(pbase);
+
+ if ( !acquire_domstatic_pages(d, psize >> PAGE_SHIFT, smfn, 0) )
I think we want to check that both pbase and psize are page aligned
first. This can be done here or earlier when reserving the pages (this
would be a previous patch).
Also, given that you can easily figure out the page from the mfn. I
think it would be better for acquire_domstatic_pages() to return an
error. This could be helpful to figure out an error.
+ {
+ printk(XENLOG_ERR
+ "%pd: cannot acquire static memory "
+ "(0x%"PRIpaddr" - 0x%"PRIpaddr").\n",
+ d, pbase, pbase + psize);
+ goto fail;
+ }
+
+ printk(XENLOG_INFO "%pd: STATIC BANK[%d] %#"PRIpaddr"-%#"PRIpaddr"\n",
bank is unsigned so s/%d/%u/
+ d, bank, pbase, pbase + psize);
+
+ /*
+ * It shall be mapped to the fixed guest RAM address rambase[i],
+ * And until it exhausts the ramsize[i], it will seek to the next
+ * rambase[i+1].
+ */
+ while ( 1 )
+ {
+ /*
+ * The current physical bank is fully mapped.
+ * Handle the next physical bank.
+ */
+ if ( gsize >= psize )
+ {
+ if ( !append_static_memory_to_bank(d, &kinfo->mem.bank[gbank],
+ smfn, psize) )
+ goto fail;
+
+ gsize = gsize - psize;
+ bank++;
+ break;
+ }
+ /*
+ * Current guest bank memory is not enough to map.
+ * Check if we have another guest bank available.
+ * gbank refers guest memory bank index.
+ */
+ else if ( (gbank + 2) > GUEST_RAM_BANKS ) {
I don't understand the +2. Can you clarify it?
Also, the coding style for Xen requires the { to be on a separate line.
+ printk("Exhausted the number of guest bank\n");
+ goto fail;
+ }
+ else
+ {
+ if ( !append_static_memory_to_bank(d, &kinfo->mem.bank[gbank],
+ smfn, gsize) )
+ goto fail;
As I may have mentionned earlier, I find the double loop quite difficult
to read. I don't think we can drop the double loop, but we can at least
try to simplify the code in the loops.
The one I can think right now is moving allocate_static_memory_to_bank()
outside of the if/else. Something like:
/* Map as much as possible the static range to the guest bank */
if ( !allocate_static_bank(.., min(psize, gize)) )
+
+ psize = psize - gsize;
+ smfn = mfn_add(smfn, gsize >> PAGE_SHIFT);
+ /* Update to the next guest bank. */
+ gbank++;
+ gsize = ramsize[gbank];
+ kinfo->mem.bank[gbank].start = rambase[gbank];
+ }
+ }
+ }
+
+ kinfo->mem.nr_banks = ++gbank;
+ kinfo->unassigned_mem -= tot_size;
+ if ( kinfo->unassigned_mem )
+ printk(XENLOG_ERR
+ "Size of \"memory\" property doesn't match up with the ones "
+ "defined in \"xen,static-mem\".\n");
We don't split the single line message accross multi-line even if the
result code is more than 80 characters long.
+
+ return;
+
+fail:
+ panic("Failed to allocate requested static memory for domain %pd."
+ "Fix the VMs configurations.\n",
Same here.
+ d);
+}
+
static int __init write_properties(struct domain *d, struct kernel_info
*kinfo,
const struct dt_device_node *node)
{
@@ -2486,8 +2619,8 @@ static int __init construct_domU(struct domain *d,
if ( !static_mem )
allocate_memory(d, &kinfo);
else
- /* TODO: allocate_static_memory(...). */
- BUG();
+ allocate_static_memory(d, &kinfo, static_mem_prop,
+ static_mem_addr_cells, static_mem_size_cells);
rc = prepare_dtb_domU(d, &kinfo);
if ( rc < 0 )
Cheers,
--
Julien Grall
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