From 58fa4433e02a394872ff83c28edea174c43e6afb Mon Sep 17 00:00:00 2001 From: Frederic Barrat Date: Tue, 11 Mar 2025 11:51:21 +1000 Subject: ppc/xive2: Add undelivered group interrupt to backlog When a group interrupt cannot be delivered, we need to: - increment the backlog counter for the group in the NVG table (if the END is configured to keep a backlog). - start a broadcast operation to set the LSMFB field on matching CPUs which can't take the interrupt now because they're running at too high a priority. [npiggin: squash in fixes from milesg] [milesg: only load the NVP if the END is !ignore] [milesg: always broadcast backlog, not only when there are precluded VPs] Signed-off-by: Frederic Barrat Signed-off-by: Michael Kowal Reviewed-by: Nicholas Piggin Signed-off-by: Nicholas Piggin --- hw/intc/xive2.c | 136 +++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 106 insertions(+), 30 deletions(-) (limited to 'hw/intc/xive2.c') diff --git a/hw/intc/xive2.c b/hw/intc/xive2.c index 41dbbdb..44d891f 100644 --- a/hw/intc/xive2.c +++ b/hw/intc/xive2.c @@ -53,7 +53,8 @@ static uint32_t xive2_nvgc_get_backlog(Xive2Nvgc *nvgc, uint8_t priority) /* * The per-priority backlog counters are 24-bit and the structure - * is stored in big endian + * is stored in big endian. NVGC is 32-bytes long, so 24-bytes from + * w2, which fits 8 priorities * 24-bits per priority. */ ptr = (uint8_t *)&nvgc->w2 + priority * 3; for (i = 0; i < 3; i++, ptr++) { @@ -62,6 +63,30 @@ static uint32_t xive2_nvgc_get_backlog(Xive2Nvgc *nvgc, uint8_t priority) return val; } +static void xive2_nvgc_set_backlog(Xive2Nvgc *nvgc, uint8_t priority, + uint32_t val) +{ + uint8_t *ptr, i; + uint32_t shift; + + if (priority > 7) { + return; + } + + if (val > 0xFFFFFF) { + val = 0xFFFFFF; + } + /* + * The per-priority backlog counters are 24-bit and the structure + * is stored in big endian + */ + ptr = (uint8_t *)&nvgc->w2 + priority * 3; + for (i = 0; i < 3; i++, ptr++) { + shift = 8 * (2 - i); + *ptr = (val >> shift) & 0xFF; + } +} + void xive2_eas_pic_print_info(Xive2Eas *eas, uint32_t lisn, GString *buf) { if (!xive2_eas_is_valid(eas)) { @@ -830,6 +855,19 @@ bool xive2_tm_irq_precluded(XiveTCTX *tctx, int ring, uint8_t priority) return true; } +void xive2_tm_set_lsmfb(XiveTCTX *tctx, int ring, uint8_t priority) +{ + uint8_t *regs = &tctx->regs[ring]; + + /* + * Called by the router during a VP-group notification when the + * thread matches but can't take the interrupt because it's + * already running at a more favored priority. It then stores the + * new interrupt priority in the LSMFB field. + */ + regs[TM_LSMFB] = priority; +} + static void xive2_router_realize(DeviceState *dev, Error **errp) { Xive2Router *xrtr = XIVE2_ROUTER(dev); @@ -870,7 +908,6 @@ static void xive2_router_end_notify(Xive2Router *xrtr, uint8_t end_blk, uint8_t priority; uint8_t format; bool found, precluded; - Xive2Nvp nvp; uint8_t nvp_blk; uint32_t nvp_idx; @@ -934,19 +971,6 @@ static void xive2_router_end_notify(Xive2Router *xrtr, uint8_t end_blk, nvp_blk = xive_get_field32(END2_W6_VP_BLOCK, end.w6); nvp_idx = xive_get_field32(END2_W6_VP_OFFSET, end.w6); - /* NVP cache lookup */ - if (xive2_router_get_nvp(xrtr, nvp_blk, nvp_idx, &nvp)) { - qemu_log_mask(LOG_GUEST_ERROR, "XIVE: no NVP %x/%x\n", - nvp_blk, nvp_idx); - return; - } - - if (!xive2_nvp_is_valid(&nvp)) { - qemu_log_mask(LOG_GUEST_ERROR, "XIVE: NVP %x/%x is invalid\n", - nvp_blk, nvp_idx); - return; - } - found = xive_presenter_notify(xrtr->xfb, format, nvp_blk, nvp_idx, xive2_end_is_ignore(&end), priority, @@ -962,10 +986,9 @@ static void xive2_router_end_notify(Xive2Router *xrtr, uint8_t end_blk, /* * If no matching NVP is dispatched on a HW thread : * - specific VP: update the NVP structure if backlog is activated - * - logical server : forward request to IVPE (not supported) + * - VP-group: update the backlog counter for that priority in the NVG */ if (xive2_end_is_backlog(&end)) { - uint8_t ipb; if (format == 1) { qemu_log_mask(LOG_GUEST_ERROR, @@ -974,19 +997,72 @@ static void xive2_router_end_notify(Xive2Router *xrtr, uint8_t end_blk, return; } - /* - * Record the IPB in the associated NVP structure for later - * use. The presenter will resend the interrupt when the vCPU - * is dispatched again on a HW thread. - */ - ipb = xive_get_field32(NVP2_W2_IPB, nvp.w2) | - xive_priority_to_ipb(priority); - nvp.w2 = xive_set_field32(NVP2_W2_IPB, nvp.w2, ipb); - xive2_router_write_nvp(xrtr, nvp_blk, nvp_idx, &nvp, 2); - - /* - * On HW, follows a "Broadcast Backlog" to IVPEs - */ + if (!xive2_end_is_ignore(&end)) { + uint8_t ipb; + Xive2Nvp nvp; + + /* NVP cache lookup */ + if (xive2_router_get_nvp(xrtr, nvp_blk, nvp_idx, &nvp)) { + qemu_log_mask(LOG_GUEST_ERROR, "XIVE: no NVP %x/%x\n", + nvp_blk, nvp_idx); + return; + } + + if (!xive2_nvp_is_valid(&nvp)) { + qemu_log_mask(LOG_GUEST_ERROR, "XIVE: NVP %x/%x is invalid\n", + nvp_blk, nvp_idx); + return; + } + + /* + * Record the IPB in the associated NVP structure for later + * use. The presenter will resend the interrupt when the vCPU + * is dispatched again on a HW thread. + */ + ipb = xive_get_field32(NVP2_W2_IPB, nvp.w2) | + xive_priority_to_ipb(priority); + nvp.w2 = xive_set_field32(NVP2_W2_IPB, nvp.w2, ipb); + xive2_router_write_nvp(xrtr, nvp_blk, nvp_idx, &nvp, 2); + } else { + Xive2Nvgc nvg; + uint32_t backlog; + + /* For groups, the per-priority backlog counters are in the NVG */ + if (xive2_router_get_nvgc(xrtr, false, nvp_blk, nvp_idx, &nvg)) { + qemu_log_mask(LOG_GUEST_ERROR, "XIVE: no NVG %x/%x\n", + nvp_blk, nvp_idx); + return; + } + + if (!xive2_nvgc_is_valid(&nvg)) { + qemu_log_mask(LOG_GUEST_ERROR, "XIVE: NVG %x/%x is invalid\n", + nvp_blk, nvp_idx); + return; + } + + /* + * Increment the backlog counter for that priority. + * We only call broadcast the first time the counter is + * incremented. broadcast will set the LSMFB field of the TIMA of + * relevant threads so that they know an interrupt is pending. + */ + backlog = xive2_nvgc_get_backlog(&nvg, priority) + 1; + xive2_nvgc_set_backlog(&nvg, priority, backlog); + xive2_router_write_nvgc(xrtr, false, nvp_blk, nvp_idx, &nvg); + + if (backlog == 1) { + XiveFabricClass *xfc = XIVE_FABRIC_GET_CLASS(xrtr->xfb); + xfc->broadcast(xrtr->xfb, nvp_blk, nvp_idx, priority); + + if (!xive2_end_is_precluded_escalation(&end)) { + /* + * The interrupt will be picked up when the + * matching thread lowers its priority level + */ + return; + } + } + } } do_escalation: -- cgit v1.1