From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.11]) (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 1B0502045B6; Tue, 29 Jul 2025 03:29:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753759765; cv=none; b=uxtMbjDzUxFi2S729uHfxCDxS5UouiG3gpfn+X6UPqNi7qjxOgV1ycxX4I/GLrCK00Clfxclg8dZ89NOw2NSmwb7xK35yVpCcHcbsZpH2XEjIdIvat2WL40A+al0RAgVJvfHA0DlBHLvY7FZhyCt538aXzo2Pxml7EQc2KQGkkY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753759765; c=relaxed/simple; bh=ANZkbK817MFJd1tmvTvtQznG5aURBb6fkvguPdy8/Rk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FHqfvUIrE98eRPAoCS18VhhxiuE7YPCTnlrFKxnZTNoOCDrjSpnrpFKZORm7o0sso0lcJX1VohJyV70lIyqn4u/RQ82uxE8tLdr9/0qiHZ1T6JAJ8pcv1n2SgB9azeYJrOBix0UPkWknDlMLEVObbRXe0D+GFRmPIh6rJM3u3NI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=HKki5wkZ; arc=none smtp.client-ip=198.175.65.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="HKki5wkZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1753759764; x=1785295764; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=ANZkbK817MFJd1tmvTvtQznG5aURBb6fkvguPdy8/Rk=; b=HKki5wkZU9EjhOGwr9/HgpdZ9L8MEyWhhIWXGhqj/0uDR+VjMTogN45k KV2Wsqz0YHM8zAkNBzvqE2xvysg8PZItlaTfCGgJdl9+R/f/IErv6a7AB tE3Aeq3vKYTbE2YYY/UY4nTDuuHbrDM3IyOsyb4BO2ZWKqaXVQXqsKhfN 4lbKtRNvD4HnGJABsvHheUgaQqfUUwddgUdjwvu+B3UPDoRkehuzFj7IM mr/8F5dMfWkwuQFxzDDh0YAp7cr9wLxoFfLKExp1qGRpE2UvvH4sGJzu7 mz3/t8rw/tXflDcak56in5UA+kB7SPYLzQcbzvweDx1i7OAjYUvR4ByQT Q==; X-CSE-ConnectionGUID: k7lGRyVnShKiR6+RJvZB3Q== X-CSE-MsgGUID: A6i+33SaSriJtrQH7aVXVQ== X-IronPort-AV: E=McAfee;i="6800,10657,11505"; a="66291914" X-IronPort-AV: E=Sophos;i="6.16,348,1744095600"; d="scan'208";a="66291914" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by orvoesa103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jul 2025 20:29:23 -0700 X-CSE-ConnectionGUID: dmmLKCIFQpqYNDG5hHfwEw== X-CSE-MsgGUID: 2RK1eSy1Q3a6Klp6VpNCRw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,348,1744095600"; d="scan'208";a="193570153" Received: from dapengmi-mobl1.ccr.corp.intel.com (HELO [10.124.240.106]) ([10.124.240.106]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jul 2025 20:29:17 -0700 Message-ID: <7dc97db7-5eea-4b65-aed3-4fc2846e13a6@linux.intel.com> Date: Tue, 29 Jul 2025 11:29:14 +0800 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 20/38] KVM: x86/pmu: Check if mediated vPMU can intercept rdpmc To: Sean Christopherson , Sandipan Das Cc: Mingwei Zhang , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Paolo Bonzini , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , Liang@google.com, Kan , "H. Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Yongwei Ma , Xiong Zhang , Jim Mattson , Zide Chen , Eranian Stephane , Shukla Manali , Nikunj Dadhania References: <20250324173121.1275209-1-mizhang@google.com> <20250324173121.1275209-21-mizhang@google.com> Content-Language: en-US From: "Mi, Dapeng" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/9/2025 11:53 PM, Sean Christopherson wrote: > On Mon, May 26, 2025, Sandipan Das wrote: >>> @@ -212,6 +212,18 @@ static void amd_pmu_refresh(struct kvm_vcpu *vcpu) >>> bitmap_set(pmu->all_valid_pmc_idx, 0, pmu->nr_arch_gp_counters); >>> } >>> >>> +static void amd_pmu_refresh(struct kvm_vcpu *vcpu) >>> +{ >>> + struct vcpu_svm *svm = to_svm(vcpu); >>> + >>> + __amd_pmu_refresh(vcpu); >>> + >>> + if (kvm_rdpmc_in_guest(vcpu)) >>> + svm_clr_intercept(svm, INTERCEPT_RDPMC); >>> + else >>> + svm_set_intercept(svm, INTERCEPT_RDPMC); >>> +} >>> + >> After putting kprobes on kvm_pmu_rdpmc(), I noticed that RDPMC instructions were >> getting intercepted for the secondary vCPUs. This happens because when secondary >> vCPUs come up, kvm_vcpu_reset() gets called after guest CPUID has been updated. >> While RDPMC interception is initially disabled in the kvm_pmu_refresh() path, it >> gets re-enabled in the kvm_vcpu_reset() path as svm_vcpu_reset() calls init_vmcb(). >> We should consider adding the following change to avoid that. > Revisiting this code after the MSR interception rework, I think we should go for > a more complete, big-hammer solution. Rather than manipulate intercepts during > kvm_pmu_refresh(), do the updates as part of the "common" recalc intercepts flow. > And then to trigger recalc on PERF_CAPABILITIES writes, turn KVM_REQ_MSR_FILTER_CHANGED > into a generic KVM_REQ_RECALC_INTERCEPTS. > > That way there's one path for calculating dynamic intercepts, which should make it > much more difficult for us to screw up things like reacting to MSR filter changes. > And providing a single path avoids needing to have a series of back-and-forth calls > between common x86 code, PMU code, and vendor code. Sounds good to me. BTW, Sean, may I know your plan about the mediated vPMU v5 patch set? Thanks.