From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-192.mta0.migadu.com (out-192.mta0.migadu.com [91.218.175.192]) (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 531A43FB14 for ; Tue, 17 Oct 2023 17:09:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="TFgn2b52" Date: Tue, 17 Oct 2023 17:09:09 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1697562555; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7Rfv7r/GuU3poBoBBegpc3MH7nKblNdFhx9LayDfN/g=; b=TFgn2b52np5IlEuu1uUS0tBRQpxK65WkA4Rmi+nvkk/K2SazzQgS5KeQwEiHqQ4qLjybb1 Dr7lvKVLwFmwGHOmJ4Gks+3K03eT7PtCqdqC4B+auUvybaYnVf/F8Ngan61k6vSXRyYqP/ 9jzXApHjjRRK96UwkrZJfelaWWrcczk= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Raghavendra Rao Ananta Cc: Sebastian Ott , Marc Zyngier , Alexandru Elisei , James Morse , Suzuki K Poulose , Paolo Bonzini , Zenghui Yu , Shaoqin Huang , Jing Zhang , Reiji Watanabe , Colton Lewis , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH v7 07/12] KVM: arm64: PMU: Set PMCR_EL0.N for vCPU based on the associated PMU Message-ID: References: <20231009230858.3444834-1-rananta@google.com> <20231009230858.3444834-8-rananta@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT On Tue, Oct 17, 2023 at 09:58:08AM -0700, Raghavendra Rao Ananta wrote: > On Mon, Oct 16, 2023 at 10:52 PM Oliver Upton wrote: > > > > On Mon, Oct 16, 2023 at 02:35:52PM -0700, Raghavendra Rao Ananta wrote: > > > > [...] > > > > > > What's the point of doing this in the first place? The implementation of > > > > kvm_vcpu_read_pmcr() is populating PMCR_EL0.N using the VM-scoped value. > > > > > > > I guess originally the change replaced read_sysreg(pmcr_el0) with > > > kvm_vcpu_read_pmcr(vcpu) to maintain consistency with others. > > > But if you and Sebastian feel that it's an overkill and directly > > > getting the value via vcpu->kvm->arch.pmcr_n is more readable, I'm > > > happy to make the change. > > > > No, I'd rather you delete the line where PMCR_EL0.N altogether. > > reset_pmcr() tries to initialize the field, but your > > kvm_vcpu_read_pmcr() winds up replacing it with pmcr_n. > > > I didn't get this comment. We still do initialize pmcr, but using the > pmcr.n read via kvm_vcpu_read_pmcr() instead of the actual system > register. You have two bits of code trying to do the exact same thing: 1) reset_pmcr() initializes __vcpu_sys_reg(vcpu, PMCR_EL0) with the N field set up. 2) kvm_vcpu_read_pmcr() takes whatever is in __vcpu_sys_reg(vcpu, PMCR_EL0), *masks out* the N field and re-initializes it with vcpu->kvm->arch.pmcr_n Why do you need (1) if you do (2)? -- Thanks, Oliver From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9DA03C46CA1 for ; Tue, 17 Oct 2023 17:09:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=NgBjdtmRE6A4c7fx2Z99QLeDjlXk5+hhMlx7JW5NegM=; b=OMNdnDL3iQI5eC s1XccVoXM8Fd3OiestYuvPdSDE0WhZtcl6m81QQL+nZoJd1lxRfQLgEQuxs0MgR65Oih78oFil0pq +M5e2bIvaHGJE7sx29qK1pQ5WNa9FrY5Q32D3RHGsnzARSGwUQNT38jJURZ1n97EmXjS87FdJkDwn 5CG+T3839GoGEUAZoT7ZgQ7t+CkVG7Es7iINEbzompVjhe3k7JO5Y+7fuc1aIa5QX69+TFBKRTpcU xwC2Lkjgb09VCD5gE1OD62zip9stfcayd0LjAI0T8enQ0advIvYLAyTWnav4UBwLQP5TNMBWe90gM oenIM3rcUgeHhfCf3wKw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qsnZL-00Csoh-2r; Tue, 17 Oct 2023 17:09:23 +0000 Received: from out-209.mta0.migadu.com ([2001:41d0:1004:224b::d1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qsnZH-00Csnj-3B for linux-arm-kernel@lists.infradead.org; Tue, 17 Oct 2023 17:09:21 +0000 Date: Tue, 17 Oct 2023 17:09:09 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1697562555; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7Rfv7r/GuU3poBoBBegpc3MH7nKblNdFhx9LayDfN/g=; b=TFgn2b52np5IlEuu1uUS0tBRQpxK65WkA4Rmi+nvkk/K2SazzQgS5KeQwEiHqQ4qLjybb1 Dr7lvKVLwFmwGHOmJ4Gks+3K03eT7PtCqdqC4B+auUvybaYnVf/F8Ngan61k6vSXRyYqP/ 9jzXApHjjRRK96UwkrZJfelaWWrcczk= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Raghavendra Rao Ananta Cc: Sebastian Ott , Marc Zyngier , Alexandru Elisei , James Morse , Suzuki K Poulose , Paolo Bonzini , Zenghui Yu , Shaoqin Huang , Jing Zhang , Reiji Watanabe , Colton Lewis , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH v7 07/12] KVM: arm64: PMU: Set PMCR_EL0.N for vCPU based on the associated PMU Message-ID: References: <20231009230858.3444834-1-rananta@google.com> <20231009230858.3444834-8-rananta@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231017_100920_431896_1CEFED1F X-CRM114-Status: GOOD ( 17.44 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gVHVlLCBPY3QgMTcsIDIwMjMgYXQgMDk6NTg6MDhBTSAtMDcwMCwgUmFnaGF2ZW5kcmEgUmFv IEFuYW50YSB3cm90ZToKPiBPbiBNb24sIE9jdCAxNiwgMjAyMyBhdCAxMDo1MuKAr1BNIE9saXZl ciBVcHRvbiA8b2xpdmVyLnVwdG9uQGxpbnV4LmRldj4gd3JvdGU6Cj4gPgo+ID4gT24gTW9uLCBP Y3QgMTYsIDIwMjMgYXQgMDI6MzU6NTJQTSAtMDcwMCwgUmFnaGF2ZW5kcmEgUmFvIEFuYW50YSB3 cm90ZToKPiA+Cj4gPiBbLi4uXQo+ID4KPiA+ID4gPiBXaGF0J3MgdGhlIHBvaW50IG9mIGRvaW5n IHRoaXMgaW4gdGhlIGZpcnN0IHBsYWNlPyBUaGUgaW1wbGVtZW50YXRpb24gb2YKPiA+ID4gPiBr dm1fdmNwdV9yZWFkX3BtY3IoKSBpcyBwb3B1bGF0aW5nIFBNQ1JfRUwwLk4gdXNpbmcgdGhlIFZN LXNjb3BlZCB2YWx1ZS4KPiA+ID4gPgo+ID4gPiBJIGd1ZXNzIG9yaWdpbmFsbHkgdGhlIGNoYW5n ZSByZXBsYWNlZCByZWFkX3N5c3JlZyhwbWNyX2VsMCkgd2l0aAo+ID4gPiBrdm1fdmNwdV9yZWFk X3BtY3IodmNwdSkgdG8gbWFpbnRhaW4gY29uc2lzdGVuY3kgd2l0aCBvdGhlcnMuCj4gPiA+IEJ1 dCBpZiB5b3UgYW5kIFNlYmFzdGlhbiBmZWVsIHRoYXQgaXQncyBhbiBvdmVya2lsbCBhbmQgZGly ZWN0bHkKPiA+ID4gZ2V0dGluZyB0aGUgdmFsdWUgdmlhIHZjcHUtPmt2bS0+YXJjaC5wbWNyX24g aXMgbW9yZSByZWFkYWJsZSwgSSdtCj4gPiA+IGhhcHB5IHRvIG1ha2UgdGhlIGNoYW5nZS4KPiA+ Cj4gPiBObywgSSdkIHJhdGhlciB5b3UgZGVsZXRlIHRoZSBsaW5lIHdoZXJlIFBNQ1JfRUwwLk4g YWx0b2dldGhlci4KPiA+IHJlc2V0X3BtY3IoKSB0cmllcyB0byBpbml0aWFsaXplIHRoZSBmaWVs ZCwgYnV0IHlvdXIKPiA+IGt2bV92Y3B1X3JlYWRfcG1jcigpIHdpbmRzIHVwIHJlcGxhY2luZyBp dCB3aXRoIHBtY3Jfbi4KPiA+Cj4gSSBkaWRuJ3QgZ2V0IHRoaXMgY29tbWVudC4gV2Ugc3RpbGwg ZG8gaW5pdGlhbGl6ZSBwbWNyLCBidXQgdXNpbmcgdGhlCj4gcG1jci5uIHJlYWQgdmlhIGt2bV92 Y3B1X3JlYWRfcG1jcigpIGluc3RlYWQgb2YgdGhlIGFjdHVhbCBzeXN0ZW0KPiByZWdpc3Rlci4K CllvdSBoYXZlIHR3byBiaXRzIG9mIGNvZGUgdHJ5aW5nIHRvIGRvIHRoZSBleGFjdCBzYW1lIHRo aW5nOgoKIDEpIHJlc2V0X3BtY3IoKSBpbml0aWFsaXplcyBfX3ZjcHVfc3lzX3JlZyh2Y3B1LCBQ TUNSX0VMMCkgd2l0aCB0aGUgTgogICAgZmllbGQgc2V0IHVwLgoKIDIpIGt2bV92Y3B1X3JlYWRf cG1jcigpIHRha2VzIHdoYXRldmVyIGlzIGluIF9fdmNwdV9zeXNfcmVnKHZjcHUsIFBNQ1JfRUww KSwKICAgICptYXNrcyBvdXQqIHRoZSBOIGZpZWxkIGFuZCByZS1pbml0aWFsaXplcyBpdCB3aXRo IHZjcHUtPmt2bS0+YXJjaC5wbWNyX24KCldoeSBkbyB5b3UgbmVlZCAoMSkgaWYgeW91IGRvICgy KT8KCi0tIApUaGFua3MsCk9saXZlcgoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX18KbGludXgtYXJtLWtlcm5lbCBtYWlsaW5nIGxpc3QKbGludXgtYXJtLWtl cm5lbEBsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZyYWRlYWQub3JnL21haWxt YW4vbGlzdGluZm8vbGludXgtYXJtLWtlcm5lbAo=