Re: [PATCH v8 12/14] powerpc/vas: Return credits after handling fault
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2020-03-23 02:50:52
Haren Myneni's on March 19, 2020 4:19 pm:
NX expects OS to return credit for send window after processing each fault. Also credit has to be returned even for fault window.
And this should be merged in the fault handler function.
quoted hunk ↗ jump to hunk
Signed-off-by: Sukadev Bhattiprolu <redacted> Signed-off-by: Haren Myneni <haren@linux.ibm.com> --- arch/powerpc/platforms/powernv/vas-fault.c | 9 +++++++++ arch/powerpc/platforms/powernv/vas-window.c | 17 +++++++++++++++++ arch/powerpc/platforms/powernv/vas.h | 1 + 3 files changed, 27 insertions(+)diff --git a/arch/powerpc/platforms/powernv/vas-fault.c b/arch/powerpc/platforms/powernv/vas-fault.c index 40e1de4..292f7ba 100644 --- a/arch/powerpc/platforms/powernv/vas-fault.c +++ b/arch/powerpc/platforms/powernv/vas-fault.c@@ -238,6 +238,10 @@ irqreturn_t vas_fault_thread_fn(int irq, void *data) memcpy(crb, fifo, CRB_SIZE); entry->stamp.nx.pswid = cpu_to_be32(FIFO_INVALID_ENTRY); entry->ccw |= cpu_to_be32(CCW0_INVALID); + /* + * Return credit for the fault window. + */
None of the comments in this patch are useful.
+ vas_return_credit(vinst->fault_win, 0);
Can you use true/false for bools?
quoted hunk ↗ jump to hunk
mutex_unlock(&vinst->mutex); pr_devel("VAS[%d] fault_fifo %p, fifo %p, fault_crbs %d\n",@@ -267,6 +271,11 @@ irqreturn_t vas_fault_thread_fn(int irq, void *data) } update_csb(window, crb); + /* + * Return credit for send window after processing + * fault CRB. + */
Any chance of a little bit of explanation how the credit system works? Or is it in the code somewhere already? I don't suppose there is a chance to batch credit updates with multiple faults? (maybe the MMIO is insignificant)
+ vas_return_credit(window, 1); } while (true); }
Thanks, Nick