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ppc/xive2: Process group backlog when pushing an OS context

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When pushing an OS context, we were already checking if there was a
pending interrupt in the IPB and sending a notification if needed.  We
also need to check if there is a pending group interrupt stored in the
NVG table. To avoid useless backlog scans, we only scan if the NVP
belongs to a group.

Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
This commit is contained in:
Frederic Barrat 2025-03-11 11:51:22 +10:00 • committed by Nicholas Piggin
parent 58fa4433e0
commit 071456d0c7
1 changed files with 97 additions and 0 deletions
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97
hw/intc/xive2.c
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@ -279,6 +279,85 @@ static void xive2_end_enqueue(Xive2End *end, uint32_t data)
end->w1 = xive_set_field32(END2_W1_PAGE_OFF, end->w1, qindex);
}
/*
* Scan the group chain and return the highest priority and group
* level of pending group interrupts.
*/
static uint8_t xive2_presenter_backlog_scan(XivePresenter *xptr,
uint8_t nvp_blk, uint32_t nvp_idx,
uint8_t first_group,
uint8_t *out_level)
{
Xive2Router *xrtr = XIVE2_ROUTER(xptr);
uint32_t nvgc_idx, mask;
uint32_t current_level, count;
uint8_t prio;
Xive2Nvgc nvgc;
for (prio = 0; prio <= XIVE_PRIORITY_MAX; prio++) {
current_level = first_group & 0xF;
while (current_level) {
mask = (1 << current_level) - 1;
nvgc_idx = nvp_idx & ~mask;
nvgc_idx |= mask >> 1;
qemu_log("fxb %s checking backlog for prio %d group idx %x\n",
__func__, prio, nvgc_idx);
if (xive2_router_get_nvgc(xrtr, false, nvp_blk, nvgc_idx, &nvgc)) {
qemu_log_mask(LOG_GUEST_ERROR, "XIVE: No NVG %x/%x\n",
nvp_blk, nvgc_idx);
return 0xFF;
}
if (!xive2_nvgc_is_valid(&nvgc)) {
qemu_log_mask(LOG_GUEST_ERROR, "XIVE: Invalid NVG %x/%x\n",
nvp_blk, nvgc_idx);
return 0xFF;
}
count = xive2_nvgc_get_backlog(&nvgc, prio);
if (count) {
*out_level = current_level;
return prio;
}
current_level = xive_get_field32(NVGC2_W0_PGONEXT, nvgc.w0) & 0xF;
}
}
return 0xFF;
}
static void xive2_presenter_backlog_decr(XivePresenter *xptr,
uint8_t nvp_blk, uint32_t nvp_idx,
uint8_t group_prio,
uint8_t group_level)
{
Xive2Router *xrtr = XIVE2_ROUTER(xptr);
uint32_t nvgc_idx, mask, count;
Xive2Nvgc nvgc;
group_level &= 0xF;
mask = (1 << group_level) - 1;
nvgc_idx = nvp_idx & ~mask;
nvgc_idx |= mask >> 1;
if (xive2_router_get_nvgc(xrtr, false, nvp_blk, nvgc_idx, &nvgc)) {
qemu_log_mask(LOG_GUEST_ERROR, "XIVE: No NVG %x/%x\n",
nvp_blk, nvgc_idx);
return;
}
if (!xive2_nvgc_is_valid(&nvgc)) {
qemu_log_mask(LOG_GUEST_ERROR, "XIVE: Invalid NVG %x/%x\n",
nvp_blk, nvgc_idx);
return;
}
count = xive2_nvgc_get_backlog(&nvgc, group_prio);
if (!count) {
return;
}
xive2_nvgc_set_backlog(&nvgc, group_prio, count - 1);
xive2_router_write_nvgc(xrtr, false, nvp_blk, nvgc_idx, &nvgc);
}
/*
* XIVE Thread Interrupt Management Area (TIMA) - Gen2 mode
*
@ -588,9 +667,13 @@ static void xive2_tctx_need_resend(Xive2Router *xrtr, XiveTCTX *tctx,
uint8_t nvp_blk, uint32_t nvp_idx,
bool do_restore)
{
XivePresenter *xptr = XIVE_PRESENTER(xrtr);
uint8_t ipb;
uint8_t backlog_level;
uint8_t group_level;
uint8_t first_group;
uint8_t backlog_prio;
uint8_t group_prio;
uint8_t *regs = &tctx->regs[TM_QW1_OS];
Xive2Nvp nvp;
@ -625,6 +708,20 @@ static void xive2_tctx_need_resend(Xive2Router *xrtr, XiveTCTX *tctx,
backlog_prio = xive_ipb_to_pipr(ipb);
backlog_level = 0;
first_group = xive_get_field32(NVP2_W0_PGOFIRST, nvp.w0);
if (first_group && regs[TM_LSMFB] < backlog_prio) {
group_prio = xive2_presenter_backlog_scan(xptr, nvp_blk, nvp_idx,
first_group, &group_level);
regs[TM_LSMFB] = group_prio;
if (regs[TM_LGS] && group_prio < backlog_prio) {
/* VP can take a group interrupt */
xive2_presenter_backlog_decr(xptr, nvp_blk, nvp_idx,
group_prio, group_level);
backlog_prio = group_prio;
backlog_level = group_level;
}
}
/*
* Compute the PIPR based on the restored state.
* It will raise the External interrupt signal if needed.