powerpc/pseries: Add kernel parameter to disable batched hcalls

This introduces a pair of kernel parameters that can be used to disable
the MULTITCE and BULK_REMOVE h-calls.

By default, those hcalls are enabled, active, and good for throughput
and performance.  The ability to disable them will be useful for some of
the PREEMPT_RT related investigation and work occurring on Power.

Signed-off-by: Will Schmidt <will_schmidt@vnet.ibm.com>
cc: Olof Johansson <olof@lixom.net>
cc: Anton Blanchard <anton@samba.org>
cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

3 files changed, 34 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index cdd2a6e8a3b7..69bb6a9c871a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -403,6 +403,10 @@ and is between 256 and 4096 characters. It is defined in the file
         bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
         bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
 
+        bulk_remove=off [PPC]  This parameter disables the use of the pSeries
+                        firmware feature for flushing multiple hpte entries
+                        at a time.
+
         c101=           [NET] Moxa C101 synchronous serial card
 
         cachesize=      [BUGS=X86-32] Override level 2 CPU cache size detection.
@@ -1490,6 +1494,10 @@ and is between 256 and 4096 characters. It is defined in the file
         mtdparts=       [MTD]
                         See drivers/mtd/cmdlinepart.c.
 
+        multitce=off    [PPC]  This parameter disables the use of the pSeries
+                        firmware feature for updating multiple TCE entries
+                        at a time.
+
         onenand.bdry=   [HW,MTD] Flex-OneNAND Boundary Configuration
 
                         Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index a77bcaed80af..fa2906a103dd 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -622,3 +622,17 @@ void iommu_init_early_pSeries(void)
         set_pci_dma_ops(&dma_iommu_ops);
 }
 
+static int __init disable_multitce(char *str)
+{
+        if (strcmp(str, "off") == 0 &&
+            firmware_has_feature(FW_FEATURE_LPAR) &&
+            firmware_has_feature(FW_FEATURE_MULTITCE)) {
+                printk(KERN_INFO "Disabling MULTITCE firmware feature\n");
+                ppc_md.tce_build = tce_build_pSeriesLP;
+                ppc_md.tce_free  = tce_free_pSeriesLP;
+                powerpc_firmware_features &= ~FW_FEATURE_MULTITCE;
+        }
+        return 1;
+}
+
+__setup("multitce=", disable_multitce);
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index f129040d974c..5d3ea9f60dd7 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -627,6 +627,18 @@ static void pSeries_lpar_flush_hash_range(unsigned long number, int local)
                 spin_unlock_irqrestore(&pSeries_lpar_tlbie_lock, flags);
 }
 
+static int __init disable_bulk_remove(char *str)
+{
+        if (strcmp(str, "off") == 0 &&
+            firmware_has_feature(FW_FEATURE_BULK_REMOVE)) {
+                        printk(KERN_INFO "Disabling BULK_REMOVE firmware feature");
+                        powerpc_firmware_features &= ~FW_FEATURE_BULK_REMOVE;
+        }
+        return 1;
+}
+
+__setup("bulk_remove=", disable_bulk_remove);
+
 void __init hpte_init_lpar(void)
 {
         ppc_md.hpte_invalidate  = pSeries_lpar_hpte_invalidate;