From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 79E84BA33; Thu, 31 Jul 2025 16:41:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753980077; cv=none; b=qBWez9CqFpeNNYcZZlFjhLiYWpJVbAB1JnlbatN1KqD6BzFjP04ReGCAM6kubouVcL8pGA2WxUCyYh98DxI1rcHzNWbL6TJvnl82Wvy3IzxilJ3bmt1XikTrfpII6f1EdmX3zT86w3ugbLDMA35l7j0Sg6VHSUsqoVQexPLCJQg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753980077; c=relaxed/simple; bh=m5uXY5lnVsSAB6lYm8kAe3A3pZTyC1KyFFSC8PRe3sc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=a/gNf5e4efAcf6FEOi9zLgw/dgxPIO9ntvJSJOyxeTg51L+KJJOhfWTXox80x0izSb8IF2D8wO/n9qn2law+FYxokmt3n7wzfXueBHuH9KyGsH4C37kwZLbxFSfS/hQzgOW8vPjN4I6o9oXokZ2QF0Px4wNNd33wcs4cds6aOXA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=SlRWJFm1; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="SlRWJFm1" Received: from [192.168.7.202] ([71.202.166.45]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 56VGefKE2183353 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Thu, 31 Jul 2025 09:40:42 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 56VGefKE2183353 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025072201; t=1753980043; bh=llH8Ua0inzYLAWwMznknRFJtwCSgP28lmR1HuFj4h1E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=SlRWJFm18Oh7B4IeeJWqEixiSNCQ8m0ItL44B/KO9AKWD3rDM1zsB/uDBf0/e8cyq AHaV+rhYSWMxFmPoaj628fAC8ZWrR9Qd8b/73K8ZO4S4M5vFEGAcldxKraTwH6ex3f RFbJMBmRzkfzBfbalmtGf+qxW1MIud0nrcI2MVA5AoKoBHhdWvD2z8BO2AD2AQM3xO wVJ02UImGXfLkAc4kJ1kR8QpmwDMJTTKFz0fNtG/Tuh4WHXMk7Y8rK79TJ3AwkFDI8 hLlq8LUf0z/RuqRQ3MtTW2ABWYqFu2PahAi5HZdq4fpyUe763wpo8/z1gMFKq5x32h m8r3hnl4L/wdg== Message-ID: <7af6dcf5-fbcd-4173-a588-38cf6c536282@zytor.com> Date: Thu, 31 Jul 2025 09:40:41 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/4] KVM: x86: Introduce MSR read/write emulation helpers To: Chao Gao Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com, seanjc@google.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com References: <20250730174605.1614792-1-xin@zytor.com> <20250730174605.1614792-3-xin@zytor.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; keydata= xsDNBGUPz1cBDACS/9yOJGojBFPxFt0OfTWuMl0uSgpwk37uRrFPTTLw4BaxhlFL0bjs6q+0 2OfG34R+a0ZCuj5c9vggUMoOLdDyA7yPVAJU0OX6lqpg6z/kyQg3t4jvajG6aCgwSDx5Kzg5 Rj3AXl8k2wb0jdqRB4RvaOPFiHNGgXCs5Pkux/qr0laeFIpzMKMootGa4kfURgPhRzUaM1vy bsMsL8vpJtGUmitrSqe5dVNBH00whLtPFM7IbzKURPUOkRRiusFAsw0a1ztCgoFczq6VfAVu raTye0L/VXwZd+aGi401V2tLsAHxxckRi9p3mc0jExPc60joK+aZPy6amwSCy5kAJ/AboYtY VmKIGKx1yx8POy6m+1lZ8C0q9b8eJ8kWPAR78PgT37FQWKYS1uAroG2wLdK7FiIEpPhCD+zH wlslo2ETbdKjrLIPNehQCOWrT32k8vFNEMLP5G/mmjfNj5sEf3IOKgMTMVl9AFjsINLHcxEQ 6T8nGbX/n3msP6A36FDfdSEAEQEAAc0WWGluIExpIDx4aW5Aenl0b3IuY29tPsLBDQQTAQgA NxYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89XBQkFo5qAAhsDBAsJCAcFFQgJCgsFFgID AQAACgkQa70OVx2uN1HUpgv/cM2fsFCQodLArMTX5nt9yqAWgA5t1srri6EgS8W3F+3Kitge tYTBKu6j5BXuXaX3vyfCm+zajDJN77JHuYnpcKKr13VcZi1Swv6Jx1u0II8DOmoDYLb1Q2ZW v83W55fOWJ2g72x/UjVJBQ0sVjAngazU3ckc0TeNQlkcpSVGa/qBIHLfZraWtdrNAQT4A1fa sWGuJrChBFhtKbYXbUCu9AoYmmbQnsx2EWoJy3h7OjtfFapJbPZql+no5AJ3Mk9eE5oWyLH+ QWqtOeJM7kKvn/dBudokFSNhDUw06e7EoVPSJyUIMbYtUO7g2+Atu44G/EPP0yV0J4lRO6EA wYRXff7+I1jIWEHpj5EFVYO6SmBg7zF2illHEW31JAPtdDLDHYcZDfS41caEKOQIPsdzQkaQ oW2hchcjcMPAfyhhRzUpVHLPxLCetP8vrVhTvnaZUo0xaVYb3+wjP+D5j/3+hwblu2agPsaE vgVbZ8Fx3TUxUPCAdr/p73DGg57oHjgezsDNBGUPz1gBDAD4Mg7hMFRQqlzotcNSxatlAQNL MadLfUTFz8wUUa21LPLrHBkUwm8RujehJrzcVbPYwPXIO0uyL/F///CogMNx7Iwo6by43KOy g89wVFhyy237EY76j1lVfLzcMYmjBoTH95fJC/lVb5Whxil6KjSN/R/y3jfG1dPXfwAuZ/4N cMoOslWkfZKJeEut5aZTRepKKF54T5r49H9F7OFLyxrC/uI9UDttWqMxcWyCkHh0v1Di8176 jjYRNTrGEfYfGxSp+3jYL3PoNceIMkqM9haXjjGl0W1B4BidK1LVYBNov0rTEzyr0a1riUrp Qk+6z/LHxCM9lFFXnqH7KWeToTOPQebD2B/Ah5CZlft41i8L6LOF/LCuDBuYlu/fI2nuCc8d m4wwtkou1Y/kIwbEsE/6RQwRXUZhzO6llfoN96Fczr/RwvPIK5SVMixqWq4QGFAyK0m/1ap4 bhIRrdCLVQcgU4glo17vqfEaRcTW5SgX+pGs4KIPPBE5J/ABD6pBnUUAEQEAAcLA/AQYAQgA JhYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89ZBQkFo5qAAhsMAAoJEGu9DlcdrjdR4C0L /RcjolEjoZW8VsyxWtXazQPnaRvzZ4vhmGOsCPr2BPtMlSwDzTlri8BBG1/3t/DNK4JLuwEj OAIE3fkkm+UG4Kjud6aNeraDI52DRVCSx6xff3bjmJsJJMb12mWglN6LjdF6K+PE+OTJUh2F dOhslN5C2kgl0dvUuevwMgQF3IljLmi/6APKYJHjkJpu1E6luZec/lRbetHuNFtbh3xgFIJx 2RpgVDP4xB3f8r0I+y6ua+p7fgOjDLyoFjubRGed0Be45JJQEn7A3CSb6Xu7NYobnxfkwAGZ Q81a2XtvNS7Aj6NWVoOQB5KbM4yosO5+Me1V1SkX2jlnn26JPEvbV3KRFcwV5RnDxm4OQTSk PYbAkjBbm+tuJ/Sm+5Yp5T/BnKz21FoCS8uvTiziHj2H7Cuekn6F8EYhegONm+RVg3vikOpn gao85i4HwQTK9/D1wgJIQkdwWXVMZ6q/OALaBp82vQ2U9sjTyFXgDjglgh00VRAHP7u1Rcu4 l75w1xInsg== In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/31/2025 3:34 AM, Chao Gao wrote: >> -fastpath_t handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu) >> +static fastpath_t handle_set_msr_irqoff(struct kvm_vcpu *vcpu, u32 msr, int reg) > > How about __handle_fastpath_set_msr_irqoff()? It's better to keep > "fastpath" in the function name to convey that this function is for > fastpath only. This is now a static function with return type fastpath_t, so I guess it's okay to remove fastpath from its name (It looks that Sean prefers shorter function names if they contains enough information). But if the protocol is to have "fastpath" in all fast path function names, I can change it. > >> { >> - u32 msr = kvm_rcx_read(vcpu); >> u64 data; >> fastpath_t ret; >> bool handled; >> @@ -2174,11 +2190,19 @@ fastpath_t handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu) >> >> switch (msr) { >> case APIC_BASE_MSR + (APIC_ICR >> 4): >> - data = kvm_read_edx_eax(vcpu); >> + if (reg == VCPU_EXREG_EDX_EAX) >> + data = kvm_read_edx_eax(vcpu); >> + else >> + data = kvm_register_read(vcpu, reg); > > ... > >> + >> handled = !handle_fastpath_set_x2apic_icr_irqoff(vcpu, data); >> break; >> case MSR_IA32_TSC_DEADLINE: >> - data = kvm_read_edx_eax(vcpu); >> + if (reg == VCPU_EXREG_EDX_EAX) >> + data = kvm_read_edx_eax(vcpu); >> + else >> + data = kvm_register_read(vcpu, reg); >> + > > Hoist this chunk out of the switch clause to avoid duplication. I thought about it, but didn't do so because the original code doesn't read the MSR data from registers when a MSR is not being handled in the fast path, which saves some cycles in most cases.