Commit 9d2ccf00 authored by Gaurav Batra's avatar Gaurav Batra Committed by Michael Ellerman
Browse files

powerpc/iommu: Limit number of TCEs to 512 for H_STUFF_TCE hcall 



Currently in tce_freemulti_pSeriesLP() there is no limit on how many
TCEs are passed to the H_STUFF_TCE hcall. This has not caused an issue
until now, but newer firmware releases have started enforcing a limit of
512 TCEs per call.

The limit is correct per the specification (PAPR v2.12 § 14.5.4.2.3).

The code has been in it's current form since it was initially merged.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarGaurav Batra <gbatra@linux.vnet.ibm.com>
Reviewed-by: default avatarBrian King <brking@linux.vnet.ibm.com>
[mpe: Tweak change log wording & add PAPR reference]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230525143454.56878-1-gbatra@linux.vnet.ibm.com
parent 81d358b1

arch/powerpc/platforms/pseries/iommu.c

+11 −2
Original line number Diff line number Diff line
@@ -317,13 +317,22 @@ static void tce_free_pSeriesLP(unsigned long liobn, long tcenum, long tceshift, 
static void tce_freemulti_pSeriesLP(struct iommu_table *tbl, long tcenum, long npages)

{

	u64 rc;

	long rpages = npages;

	unsigned long limit;



	if (!firmware_has_feature(FW_FEATURE_STUFF_TCE))

		return tce_free_pSeriesLP(tbl->it_index, tcenum,

					  tbl->it_page_shift, npages);



	do {

		limit = min_t(unsigned long, rpages, 512);



		rc = plpar_tce_stuff((u64)tbl->it_index,

			     (u64)tcenum << tbl->it_page_shift, 0, npages);

				     (u64)tcenum << tbl->it_page_shift, 0, limit);



		rpages -= limit;

		tcenum += limit;

	} while (rpages > 0 && !rc);



	if (rc && printk_ratelimit()) {

		printk("tce_freemulti_pSeriesLP: plpar_tce_stuff failed\n");