Hi Marc Thanks for the comments On 8/27/2018 3:01 AM, Marc Zyngier Wrote: > [I'm travelling, so expect some major delays in responding to email] > > Hi Jia, > > On Sun, 26 Aug 2018 10:00:51 +0100, > Jia He <[email protected]> wrote: >> >> There is a WARN_ON when my QDF2400 server boots up (pagesize is 4k) > > [snip] > >> In its_alloc_lpi_tables, lpi_id_bits is 24, without this patch, >> its_allocate_prop_table will try to allocate 16M(order 12 if >> pagesize=4k). Thus it causes the WARN_ON. > > Gah! QDF and its 24bit INTIDs... Making life hell for everyone ;-) > > Sorry for breaking it.
np, maybe QDF2400 is a little bit special > >> >> This patch fixes it by limiting the lpi_id_bits. >> >> Signed-off-by: Jia He <[email protected]> >> --- >> drivers/irqchip/irq-gic-v3-its.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/irqchip/irq-gic-v3-its.c >> b/drivers/irqchip/irq-gic-v3-its.c >> index 316a575..79e6993 100644 >> --- a/drivers/irqchip/irq-gic-v3-its.c >> +++ b/drivers/irqchip/irq-gic-v3-its.c >> @@ -1624,8 +1624,11 @@ static void its_free_prop_table(struct page >> *prop_page) >> static int __init its_alloc_lpi_tables(void) >> { >> phys_addr_t paddr; >> + u32 max_bits; /*max order limitation in alloc_page*/ >> >> - lpi_id_bits = GICD_TYPER_ID_BITS(gic_rdists->gicd_typer); >> + max_bits = PAGE_SHIFT + MAX_ORDER - 1; >> + lpi_id_bits = min_t(u32, max_bits, >> + GICD_TYPER_ID_BITS(gic_rdists->gicd_typer)); >> gic_rdists->prop_page = its_allocate_prop_table(GFP_NOWAIT); >> if (!gic_rdists->prop_page) { >> pr_err("Failed to allocate PROPBASE\n"); >> -- >> 1.8.3.1 >> > > I find it rather odd that we end-up with different interrupt ranges > depending on the CPU page size. Also, allocating that much memory for > LPIs is rather pointless, as we actually have a pretty low limit of > interrupts the system can deal with (see IRQ_BITMAP_BITS, which is > slightly more than 8k). I've so far seen *one* request to push it up, > but I doubt that it is a real use case. > > Capping lpi_id_bits at 16 (which is what we had before) is plenty, > will save a some memory, and gives some margin before we need to push > it up again. Do you want me to revert commit fe8e93504 to cap the lpi_id_bits to no greater than ITS_MAX_LPI_NRBITS(16) instead this patch? -- Cheers, Jia
