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Tue, 6 Jul 2021 14:52:48 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1m0mRK-00BkmS-Ha; Tue, 06 Jul 2021 15:52:46 +0100 Date: Tue, 06 Jul 2021 15:52:46 +0100 Message-ID: <87y2aj7av5.wl-maz@kernel.org> From: Marc Zyngier To: Alexandre Chartre Subject: Re: [PATCH] KVM: arm64: Disabling disabled PMU counters wastes a lot of time In-Reply-To: References: <20210628161925.401343-1-alexandre.chartre@oracle.com> <878s2tavks.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: alexandre.chartre@oracle.com, will@kernel.org, catalin.marinas@arm.com, alexandru.elisei@arm.com, james.morse@arm.com, suzuki.poulose@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, konrad.wilk@oracle.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: kvm@vger.kernel.org, catalin.marinas@arm.com, konrad.wilk@oracle.com, will@kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu T24gVHVlLCAwNiBKdWwgMjAyMSAxNDo1MDozNSArMDEwMCwKQWxleGFuZHJlIENoYXJ0cmUgPGFs ZXhhbmRyZS5jaGFydHJlQG9yYWNsZS5jb20+IHdyb3RlOgo+IAo+IAo+IEhpIE1hcmMsCj4gCj4g T24gNi8yOS8yMSAzOjE2IFBNLCBBbGV4YW5kcmUgQ2hhcnRyZSB3cm90ZToKPiA+IE9uIDYvMjkv MjEgMTE6MDYgQU0sIE1hcmMgWnluZ2llciB3cm90ZQo+ID4gWy4uLl0KPiA+PiBTb8KgdGhlwqBz eXNyZWfCoGlzwqB0aGXCoG9ubHnCoHRoaW5nwqB3ZcKgc2hvdWxkwqBjb25zaWRlcizCoGFuZMKg ScKgdGhpbmvCoHdlCj4gPj4gc2hvdWxkwqBkcm9wwqB0aGXCoHVzZWxlc3PCoG1hc2tpbmcuwqBU aGVyZcKgaXPCoGF0wqBsZWFzdMKgYW5vdGhlcsKgaW5zdGFuY2XCoG9mCj4gPj4gdGhpc8KgaW7C oHRoZcKgUE1VwqBjb2RlwqAoa3ZtX3BtdV9vdmVyZmxvd19zdGF0dXMoKSkswqBhbmTCoGFwYXJ0 wqBmcm9tCj4gPj4ga3ZtX3BtdV92Y3B1X3Jlc2V0KCkswqBvbmx5wqB0aGXCoHN5c3JlZ8KgYWNj ZXNzb3JzwqBzaG91bGTCoGNhcmXCoGFib3V0wqB0aGUKPiA+PiBtYXNraW5nwqB0b8Kgc2FuaXRp c2XCoGFjY2Vzc2VzLgo+ID4+IAo+ID4+IFdoYXTCoGRvwqB5b3XCoHRoaW5rPwo+ID4+IAo+ID4g Cj4gPiBJwqB0aGlua8KgeW91wqBhcmXCoHJpZ2h0LsKgUE1DTlRFTlNFVF9FTDDCoGlzwqBhbHJl YWR5wqBtYXNrZWTCoHdpdGjCoGt2bV9wbXVfdmFsaWRfY291bnRlcl9tYXNrKCkKPiA+IHNvwqB0 aGVyZSdzwqBlZmZlY3RpdmVsecKgbm/CoG5lZWTCoHRvwqBtYXNrwqBpdMKgYWdhaW7CoHdoZW7C oHdlwqB1c2XCoGl0LsKgScKgd2lsbMKgc2VuZMKgYW7CoGFkZGl0aW9uYWwKPiA+IHBhdGNowqAo b27CoHRvcMKgb2bCoHRoaXPCoG9uZSnCoHRvwqByZW1vdmXCoHVzZWxlc3PCoG1hc2tpbmcuwqBC YXNpY2FsbHkswqBjaGFuZ2VzwqB3b3VsZMKgYmU6Cj4gCj4gSSBoYWQgYSBjbG9zZXIgbG9vayBh bmQgd2UgY2FuJ3QgcmVtb3ZlIHRoZSBtYXNrLiBUaGUgYWNjZXNzCj4gZnVuY3Rpb25zIChmb3Ig cG1jbnRlbiwgcG1pbnRlbiwgcG1vdnMpLCBjbGVhciBvciBzZXQgb25seSB0aGUKPiBzcGVjaWZp ZWQgdmFsaWQgY291bnRlciBiaXRzLiBUaGlzIG1lYW5zIHRoYXQgYml0cyBvdGhlciB0aGFuIHRo ZQo+IHZhbGlkIGNvdW50ZXIgYml0cyBuZXZlciBjaGFuZ2UgaW4gX192Y3B1X3N5c19yZWcoKSwg YW5kIHRob3NlIGJpdHMKPiBhcmUgbm90IG5lY2Vzc2FyaWx5IHplcm8gYmVjYXVzZSB0aGUgaW5p dGlhbCB2YWx1ZSBpcwo+IDB4MWRlN2VjN2VkYmFkYzBkZVVMTCAoc2V0IGJ5IHJlc2V0X3Vua25v d24oKSkuCgpUaGF0J3MgYSBidWcgdGhhdCBzaG91bGQgYmUgZml4ZWQgb24gaXRzIG93bi4gQml0 cyB0aGF0IGFyZSBSQVovV0kgaW4KdGhlIGFyY2hpdGVjdHVyZSBzaG91bGRuJ3QgYmUga2VwdCBp biB0aGUgc2hhZG93IHJlZ2lzdGVycyB0aGUgZmlyc3QKcGxhY2UuIEknbGwgaGF2ZSBhIGxvb2su Cgo+IFNvIEkgd2lsbCByZXN1Ym1pdCBpbml0aWFsIHBhdGNoLCB3aXRoIGp1c3QgdGhlIGNvbW1p dCBtZXNzYWdlCj4gY2hhbmdlcy4KClBsZWFzZSBkb24ndC4gSSdtIG5vdCBwYXBlcmluZyBvdmVy IHRoaXMga2luZCBvZiBidWcuCgpUaGFua3MsCgoJTS4KCi0tIApXaXRob3V0IGRldmlhdGlvbiBm cm9tIHRoZSBub3JtLCBwcm9ncmVzcyBpcyBub3QgcG9zc2libGUuCl9fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmt2bWFybSBtYWlsaW5nIGxpc3QKa3ZtYXJt QGxpc3RzLmNzLmNvbHVtYmlhLmVkdQpodHRwczovL2xpc3RzLmNzLmNvbHVtYmlhLmVkdS9tYWls bWFuL2xpc3RpbmZvL2t2bWFybQo=