From patchwork Tue Nov 23 09:51:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicholas Piggin X-Patchwork-Id: 1558421 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20210112 header.b=l2zw/C4F; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=2404:9400:2:0:216:3eff:fee1:b9f1; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org; receiver=) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee1:b9f1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4Hyzzz4scxz9sCD for ; Tue, 23 Nov 2021 20:56:15 +1100 (AEDT) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Hyzzz3JTzz3df7 for ; Tue, 23 Nov 2021 20:56:15 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20210112 header.b=l2zw/C4F; dkim-atps=neutral X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gmail.com (client-ip=2607:f8b0:4864:20::62c; helo=mail-pl1-x62c.google.com; envelope-from=npiggin@gmail.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20210112 header.b=l2zw/C4F; dkim-atps=neutral Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Hyzw84zYnz2ymP for ; Tue, 23 Nov 2021 20:52:56 +1100 (AEDT) Received: by mail-pl1-x62c.google.com with SMTP id b13so16633478plg.2 for ; Tue, 23 Nov 2021 01:52:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=8PMwwqEDOPR27ECCIKy4w92qtS2Ye0TbAvTvCAlNKOk=; b=l2zw/C4FKchvnn7Jg3HA2tAIBxgMQ0vYS3lD76ZIDbDl0QB9Vf0A1kxP1z4ReJBh9Y ApO51THBpDa0x48eS4S5FU2suJwATJCHq1plfn7lpRumtnnpfpv6wC9p1v8bYyiy4Y/r bcWbUwHwnmFZ/zCzSC8dlPE9itO6l+yRiH0fApY2n68jevQzIjYJU/A58hL+9bdaacu0 SA5FCXeRKKL9qc/9l6FOODBzCy8yk8R9OPipJYpH2+tLtZ8SA3QbOIerkQxhP4FYvwHE czky7QhkxBFlJgA/rbJYXBJjLL7qoveg6DGMdRx10oCiC0tZnE5lWisALf9dMztPD9PB U/nQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=8PMwwqEDOPR27ECCIKy4w92qtS2Ye0TbAvTvCAlNKOk=; b=CyjxmRamJVchJnbsTCeSN5I8U74fDE9UrForxALAvWhDrlb0SCdOjvdJqCXVjePQR7 PpoKyVTos/RQTWL/df66MhBO2Ki/kCQq5LckEVPLbNPBbs1DlyBi85qEyV2ZSOS+I+jO lcgOpenq5A2Xr4yN/Kl1xlHwbsUId8R1+vVfv08/PgcSJHtrXdzQT/Z50OVhpdfesR+Y ZdbzZ3KLfRJZvrSRHWTkVRFuuckfKE0PmBrwEN+FFvcxGkK5bEoFFQWBxZz2+BCVLGpw 2Qxeb2ZBWDYp8Leb1WPrNXHNGvsdOoR0TcIXfnXoB0JMD42BzMjNqXVIgtWXMD3eBu0p jtRg== X-Gm-Message-State: AOAM531AmN3xhw/spto1nHxP12pJvuU+NgcrwBbZqk4uO3ZTUOxbRGoJ OxQChqGRyuCRKoJEDyyHKXlOHtzBGGROPA== X-Google-Smtp-Source: ABdhPJxojIIbolujvrQLFERQ+SLN1dlbihqrTu0kq3trVD0c1amDpmJYWsv4N2y/OOujuR+OJ31iXA== X-Received: by 2002:a17:902:d505:b0:141:f5f7:848e with SMTP id b5-20020a170902d50500b00141f5f7848emr5273632plg.72.1637661175039; Tue, 23 Nov 2021 01:52:55 -0800 (PST) Received: from bobo.ibm.com ([124.170.11.53]) by smtp.gmail.com with ESMTPSA id j8sm12662176pfc.8.2021.11.23.01.52.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Nov 2021 01:52:54 -0800 (PST) From: Nicholas Piggin To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v4 06/53] KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit Date: Tue, 23 Nov 2021 19:51:44 +1000 Message-Id: <20211123095231.1036501-7-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20211123095231.1036501-1-npiggin@gmail.com> References: <20211123095231.1036501-1-npiggin@gmail.com> MIME-Version: 1.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nicholas Piggin , Fabiano Rosas Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" mftb is serialising (dispatch next-to-complete) so it is heavy weight for a mfspr. Avoid reading it multiple times in the entry or exit paths. A small number of cycles delay to timers is tolerable. Reviewed-by: Fabiano Rosas Signed-off-by: Nicholas Piggin --- arch/powerpc/kvm/book3s_hv.c | 4 ++-- arch/powerpc/kvm/book3s_hv_p9_entry.c | 5 +++-- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 3322edbafc64..5fc0c168a39a 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3940,7 +3940,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, * * XXX: Another day's problem. */ - mtspr(SPRN_DEC, vcpu->arch.dec_expires - mftb()); + mtspr(SPRN_DEC, vcpu->arch.dec_expires - tb); if (kvmhv_on_pseries()) { /* @@ -4063,7 +4063,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, vc->in_guest = 0; next_timer = timer_get_next_tb(); - set_dec(next_timer - mftb()); + set_dec(next_timer - tb); /* We may have raced with new irq work */ if (test_irq_work_pending()) set_dec(1); diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c b/arch/powerpc/kvm/book3s_hv_p9_entry.c index 0ff9ddb5e7ca..bd8cf0a65ce8 100644 --- a/arch/powerpc/kvm/book3s_hv_p9_entry.c +++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c @@ -203,7 +203,8 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc unsigned long host_dawr1; unsigned long host_dawrx1; - hdec = time_limit - mftb(); + tb = mftb(); + hdec = time_limit - tb; if (hdec < 0) return BOOK3S_INTERRUPT_HV_DECREMENTER; @@ -215,7 +216,7 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc vcpu->arch.ceded = 0; if (vc->tb_offset) { - u64 new_tb = mftb() + vc->tb_offset; + u64 new_tb = tb + vc->tb_offset; mtspr(SPRN_TBU40, new_tb); tb = mftb(); if ((tb & 0xffffff) < (new_tb & 0xffffff))