From 60075068ea6340e89a4b0cd4bd79c6ee3de44893 Mon Sep 17 00:00:00 2001 From: Curtis Dunham Date: Thu, 9 Mar 2017 17:30:59 +0000 Subject: [PATCH] arm, dev: add basic support for GICC_BPR register The Binary Point Register (BPR) specifies which bits belong to the group priority field (which are used for preemption) and which to the subpriority field (which are ignored for preemption). Change-Id: If51e669d23b49047b69b82ab363dd01a936cc93b Reviewed-by: Andreas Sandberg Reviewed-on: https://gem5-review.googlesource.com/2443 Maintainer: Andreas Sandberg Reviewed-by: Weiping Liao --- src/dev/arm/gic_pl390.cc | 26 +++++++++++++++++++++----- src/dev/arm/gic_pl390.hh | 5 +++++ 2 files changed, 26 insertions(+), 5 deletions(-) diff --git a/src/dev/arm/gic_pl390.cc b/src/dev/arm/gic_pl390.cc index e7f3e32ef..c114604ab 100644 --- a/src/dev/arm/gic_pl390.cc +++ b/src/dev/arm/gic_pl390.cc @@ -83,7 +83,7 @@ Pl390::Pl390(const Params *p) iccrpr[x] = 0xff; cpuEnabled[x] = false; cpuPriority[x] = 0xff; - cpuBpr[x] = 0; + cpuBpr[x] = GICC_BPR_MINIMUM; // Initialize cpu highest int cpuHighestInt[x] = SPURIOUS_INT; postIntEvent[x] = new PostIntEvent(*this, x); @@ -538,9 +538,13 @@ Pl390::writeCpu(ContextID ctx, Addr daddr, uint32_t data) case GICC_PMR: cpuPriority[ctx] = data; break; - case GICC_BPR: - cpuBpr[ctx] = data; + case GICC_BPR: { + auto bpr = data & 0x7; + if (bpr < GICC_BPR_MINIMUM) + bpr = GICC_BPR_MINIMUM; + cpuBpr[ctx] = bpr; break; + } case GICC_EOIR: { const IAR iar = data; if (iar.ack_id < SGI_MAX) { @@ -666,6 +670,17 @@ Pl390::genSwiMask(int cpu) return ULL(0x0101010101010101) << cpu; } +uint8_t +Pl390::getCpuPriority(unsigned cpu) +{ + // see Table 3-2 in IHI0048B.b (GICv2) + // mask some low-order priority bits per BPR value + // NB: the GIC prioritization scheme is upside down: + // lower values are higher priority; masking off bits + // actually creates a higher priority, not lower. + return cpuPriority[cpu] & (0xff00 >> (7 - cpuBpr[cpu])); +} + void Pl390::updateIntState(int hint) { @@ -676,7 +691,7 @@ Pl390::updateIntState(int hint) /*@todo use hint to do less work. */ int highest_int = SPURIOUS_INT; // Priorities below that set in GICC_PMR can be ignored - uint8_t highest_pri = cpuPriority[cpu]; + uint8_t highest_pri = getCpuPriority(cpu); // Check SGIs for (int swi = 0; swi < SGI_MAX; swi++) { @@ -733,7 +748,8 @@ Pl390::updateIntState(int hint) /* @todo make this work for more than one cpu, need to handle 1:N, N:N * models */ - if (enabled && cpuEnabled[cpu] && (highest_pri < cpuPriority[cpu]) && + if (enabled && cpuEnabled[cpu] && + (highest_pri < getCpuPriority(cpu)) && !(getActiveInt(cpu, intNumToWord(highest_int)) & (1 << intNumToBit(highest_int)))) { diff --git a/src/dev/arm/gic_pl390.hh b/src/dev/arm/gic_pl390.hh index 210f91cfc..8beb5e2d5 100644 --- a/src/dev/arm/gic_pl390.hh +++ b/src/dev/arm/gic_pl390.hh @@ -111,6 +111,10 @@ class Pl390 : public BaseGic static const int INT_LINES_MAX = 1020; static const int GLOBAL_INT_LINES = INT_LINES_MAX - SGI_MAX - PPI_MAX; + /** minimum value for Binary Point Register ("IMPLEMENTATION DEFINED"); + chosen for consistency with Linux's in-kernel KVM GIC model */ + static const int GICC_BPR_MINIMUM = 2; + BitUnion32(SWI) Bitfield<3,0> sgi_id; Bitfield<23,16> cpu_list; @@ -276,6 +280,7 @@ class Pl390 : public BaseGic /** CPU priority */ uint8_t cpuPriority[CPU_MAX]; + uint8_t getCpuPriority(unsigned cpu); // BPR-adjusted priority value /** Binary point registers */ uint8_t cpuBpr[CPU_MAX]; -- 2.30.2