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[124.171.72.210]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7f8c1c644b1sm6672669a12.42.2024.11.18.20.20.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Nov 2024 20:20:32 -0800 (PST) Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 19 Nov 2024 14:20:25 +1000 Message-Id: Cc: , , , , , , , , , Subject: Re: [PATCH 05/14] ppc/xive2: Process group backlog when pushing an OS context From: "Nicholas Piggin" To: "Michael Kowal" , X-Mailer: aerc 0.18.2 References: <20241015211329.21113-1-kowal@linux.ibm.com> <20241015211329.21113-6-kowal@linux.ibm.com> In-Reply-To: <20241015211329.21113-6-kowal@linux.ibm.com> Received-SPF: pass client-ip=2607:f8b0:4864:20::c32; envelope-from=npiggin@gmail.com; helo=mail-oo1-xc32.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed Oct 16, 2024 at 7:13 AM AEST, Michael Kowal wrote: > From: Frederic Barrat > > 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 > Signed-off-by: Michael Kowal > --- > hw/intc/xive2.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 97 insertions(+), 3 deletions(-) > > diff --git a/hw/intc/xive2.c b/hw/intc/xive2.c > index a6dc6d553f..7130892482 100644 > --- a/hw/intc/xive2.c > +++ b/hw/intc/xive2.c > @@ -279,6 +279,85 @@ static void xive2_end_enqueue(Xive2End *end, uint32_= t data) > end->w1 =3D xive_set_field32(END2_W1_PAGE_OFF, end->w1, qindex); > } > =20 > +/* > + * Scan the group chain and return the highest priority and group > + * level of pending group interrupts. > + */ > +static uint8_t xive2_presenter_backlog_check(XivePresenter *xptr, > + uint8_t nvp_blk, uint32_t n= vp_idx, > + uint8_t first_group, > + uint8_t *out_level) Could we call that xive2_presenter_backlog_scan(), which I think matches how the specification refers to it. Thanks, Nick > +{ > + Xive2Router *xrtr =3D XIVE2_ROUTER(xptr); > + uint32_t nvgc_idx, mask; > + uint32_t current_level, count; > + uint8_t prio; > + Xive2Nvgc nvgc; > + > + for (prio =3D 0; prio <=3D XIVE_PRIORITY_MAX; prio++) { > + current_level =3D first_group & 0xF; > + > + while (current_level) { > + mask =3D (1 << current_level) - 1; > + nvgc_idx =3D nvp_idx & ~mask; > + nvgc_idx |=3D 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, &n= vgc)) { > + 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 =3D xive2_nvgc_get_backlog(&nvgc, prio); > + if (count) { > + *out_level =3D current_level; > + return prio; > + } > + current_level =3D 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_i= dx, > + uint8_t group_prio, > + uint8_t group_level) > +{ > + Xive2Router *xrtr =3D XIVE2_ROUTER(xptr); > + uint32_t nvgc_idx, mask, count; > + Xive2Nvgc nvgc; > + > + group_level &=3D 0xF; > + mask =3D (1 << group_level) - 1; > + nvgc_idx =3D nvp_idx & ~mask; > + nvgc_idx |=3D 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 =3D 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 > * > @@ -588,8 +667,9 @@ static void xive2_tctx_need_resend(Xive2Router *xrtr,= XiveTCTX *tctx, > uint8_t nvp_blk, uint32_t nvp_idx, > bool do_restore) > { > - uint8_t ipb, backlog_level; > - uint8_t backlog_prio; > + XivePresenter *xptr =3D XIVE_PRESENTER(xrtr); > + uint8_t ipb, backlog_level, group_level, first_group; > + uint8_t backlog_prio, group_prio; > uint8_t *regs =3D &tctx->regs[TM_QW1_OS]; > Xive2Nvp nvp; > =20 > @@ -624,8 +704,22 @@ static void xive2_tctx_need_resend(Xive2Router *xrtr= , XiveTCTX *tctx, > backlog_prio =3D xive_ipb_to_pipr(ipb); > backlog_level =3D 0; > =20 > + first_group =3D xive_get_field32(NVP2_W0_PGOFIRST, nvp.w0); > + if (first_group && regs[TM_LSMFB] < backlog_prio) { > + group_prio =3D xive2_presenter_backlog_check(xptr, nvp_blk, nvp_= idx, > + first_group, &group_l= evel); > + regs[TM_LSMFB] =3D 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 =3D group_prio; > + backlog_level =3D group_level; > + } > + } > + > /* > - * Compute the PIPR based on the restored state. > + * Compute the PIPR based on the restored state. > * It will raise the External interrupt signal if needed. > */ > xive_tctx_pipr_update(tctx, TM_QW1_OS, backlog_prio, backlog_level);