From patchwork Tue Nov 5 18:30:39 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Haris Okanovic X-Patchwork-Id: 13863352 Received: from smtp-fw-9106.amazon.com (smtp-fw-9106.amazon.com [207.171.188.206]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3812A1E3DE6; Tue, 5 Nov 2024 18:32:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=207.171.188.206 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730831535; cv=none; b=WJuxbhr76KoOEGahWSuve12GaRQ5JMjAHW2tpS+69njxANIn92Q7pEU1roVtCEy5S+gG34u2Z6pTnZHx8sEHnz1YrNUpmYT9aelPHDWcKavSNUKRXTREeOhzkuj2wvbyrH9r7Kv0t/IZ2qMxhPivkj48sjs/1Uh2l78CGyqT1YA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730831535; c=relaxed/simple; bh=fBp3cBImyKuDZ79nZuK4LWeumA4FRziZpF4LixBVSag=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=A9OA3ZPwV0eAVnp1+AcrBonWGGYXPTjonhSdmM/iWRJFs28g5UiFdnHmd+Vr8iiPwEAa3j5FBCakMX4dPnfQ0ohhxNRdSQtJFXjvIVgfc6O4EQJ/TwD525Jt3Kg5jIm45P8s5MqrpTVIJUP6z325RS8jCmPjseU2ouudX7frVUw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.com; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=accik1HK; arc=none smtp.client-ip=207.171.188.206 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="accik1HK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1730831534; x=1762367534; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=jU1idzmOqOXlXb1t2IMpZrPTuLA9eFztDBmS3LLVVOw=; b=accik1HKQzUKKKqjDWXwXHuwoB92Oc5ZKGojZTYK/l3c82kwqFmkIJIP zlR2qB8DacEKx0IVFBAd8mqq32YufSA3YfNbztdnMMTuIrYlaMp/5sbFi KfVXUdfbBpKZDAWO5WjygmZQCBR53OQdXPgn4Oxh2kzl3M7NHA8paiGpc M=; X-IronPort-AV: E=Sophos;i="6.11,260,1725321600"; d="scan'208";a="773030717" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.25.36.210]) by smtp-border-fw-9106.sea19.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Nov 2024 18:32:13 +0000 Received: from EX19MTAUWA001.ant.amazon.com [10.0.21.151:34625] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.28.125:2525] with esmtp (Farcaster) id f9c0b0d1-8be1-4e25-ab5f-c68efeaab89c; Tue, 5 Nov 2024 18:32:12 +0000 (UTC) X-Farcaster-Flow-ID: f9c0b0d1-8be1-4e25-ab5f-c68efeaab89c Received: from EX19D001UWA003.ant.amazon.com (10.13.138.211) by EX19MTAUWA001.ant.amazon.com (10.250.64.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Tue, 5 Nov 2024 18:32:12 +0000 Received: from u34cccd802f2d52.amazon.com (10.106.239.17) by EX19D001UWA003.ant.amazon.com (10.13.138.211) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.35; Tue, 5 Nov 2024 18:32:06 +0000 From: Haris Okanovic To: , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH 3/5] arm64: refactor delay() to enable polling for value Date: Tue, 5 Nov 2024 12:30:39 -0600 Message-ID: <20241105183041.1531976-4-harisokn@amazon.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241105183041.1531976-1-harisokn@amazon.com> References: <20240925232425.2763385-1-ankur.a.arora@oracle.com> <20241105183041.1531976-1-harisokn@amazon.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D033UWA004.ant.amazon.com (10.13.139.85) To EX19D001UWA003.ant.amazon.com (10.13.138.211) Refactor arm64's delay() to poll for a mask/value condition (vcond) in it's wfet(), wfe(), and relaxed polling loops. Signed-off-by: Haris Okanovic --- arch/arm64/lib/delay.c | 70 ++++++++++++++++++++++++++++++------------ 1 file changed, 50 insertions(+), 20 deletions(-) diff --git a/arch/arm64/lib/delay.c b/arch/arm64/lib/delay.c index cb2062e7e234..a7c3040af316 100644 --- a/arch/arm64/lib/delay.c +++ b/arch/arm64/lib/delay.c @@ -14,43 +14,73 @@ #include #include +#include -#define USECS_TO_CYCLES(time_usecs) \ - xloops_to_cycles((time_usecs) * 0x10C7UL) - -static inline unsigned long xloops_to_cycles(unsigned long xloops) +static inline u64 xloops_to_cycles(u64 xloops) { return (xloops * loops_per_jiffy * HZ) >> 32; } -void __delay(unsigned long cycles) +#define USECS_TO_XLOOPS(time_usecs) \ + ((time_usecs) * 0x10C7UL) + +#define USECS_TO_CYCLES(time_usecs) \ + xloops_to_cycles(USECS_TO_XLOOPS(time_usecs)) + +#define NSECS_TO_XLOOPS(time_nsecs) \ + ((time_nsecs) * 0x10C7UL) + +#define NSECS_TO_CYCLES(time_nsecs) \ + xloops_to_cycles(NSECS_TO_XLOOPS(time_nsecs)) + +static unsigned long __delay_until_ul(u64 cycles, unsigned long* addr, unsigned long mask, unsigned long val) { - cycles_t start = get_cycles(); + u64 start = get_cycles(); + unsigned long cur; if (alternative_has_cap_unlikely(ARM64_HAS_WFXT)) { u64 end = start + cycles; - /* - * Start with WFIT. If an interrupt makes us resume - * early, use a WFET loop to complete the delay. - */ - wfit(end); - while ((get_cycles() - start) < cycles) + do { + cur = __READ_ONCE_EX(*addr); + if ((cur & mask) == val) { + break; + } wfet(end); - } else if (arch_timer_evtstrm_available()) { - const cycles_t timer_evt_period = + } while ((get_cycles() - start) < cycles); + } else if (arch_timer_evtstrm_available()) { + const u64 timer_evt_period = USECS_TO_CYCLES(ARCH_TIMER_EVT_STREAM_PERIOD_US); - while ((get_cycles() - start + timer_evt_period) < cycles) + do { + cur = __READ_ONCE_EX(*addr); + if ((cur & mask) == val) { + break; + } wfe(); + } while ((get_cycles() - start + timer_evt_period) < cycles); + } else { + do { + cur = __READ_ONCE_EX(*addr); + if ((cur & mask) == val) { + break; + } + cpu_relax(); + } while ((get_cycles() - start) < cycles); } - while ((get_cycles() - start) < cycles) - cpu_relax(); + return cur; +} + +void __delay(unsigned long cycles) +{ + /* constant word for wfet()/wfe() to poll */ + unsigned long dummy ____cacheline_aligned = 0; + __delay_until_ul(cycles, &dummy, 0, 1); } EXPORT_SYMBOL(__delay); -inline void __const_udelay(unsigned long xloops) +void __const_udelay(unsigned long xloops) { __delay(xloops_to_cycles(xloops)); } @@ -58,12 +88,12 @@ EXPORT_SYMBOL(__const_udelay); void __udelay(unsigned long usecs) { - __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */ + __delay(USECS_TO_CYCLES(usecs)); } EXPORT_SYMBOL(__udelay); void __ndelay(unsigned long nsecs) { - __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */ + __delay(NSECS_TO_CYCLES(nsecs)); } EXPORT_SYMBOL(__ndelay);