From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20D983563EB for ; Fri, 5 Jun 2026 14:18:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780669134; cv=none; b=n14geUFcflh1zb9UJHW2WrXwBPGS3Ve3iyG8ALRVZL2Wj0bLq6cqY4Rt75ebLo0c+UQpV46vKDovez695oE5tOtOf2B1K3XuOJB3xN2YUze3rSRvNPMCuoNudrsi3fwZWmRT3jN2qe8ur30N9K1qYuME/Uwou/GP2vS+k9Qsjd4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780669134; c=relaxed/simple; bh=TsTp+FBRvJpUoGimVtYkeJLacs7aQtLDqjxnfkcJZzo=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=KmhW9eZ3TxDAzelFmEI8hkXNB8hL48bKPBgRb5MHBi3v/VB7cUyTI58geq4yO9SuqsG9ZodQZwZ9CJZ5RNrIzDq6fOStIMSWpyhRuU/Zu8k2EiPLpw7byQ4c0Z1+sbTIxDHS9ImD6FWHL7qzY48jOI78XzgPpJDnL1QCdHswsDA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de; spf=pass smtp.mailfrom=suse.de; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=twdh3Ycp; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=aje03b7T; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=bcgFYDsR; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=0lw9JYz+; arc=none smtp.client-ip=195.135.223.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="twdh3Ycp"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="aje03b7T"; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="bcgFYDsR"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="0lw9JYz+" Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 0BAD36B37B; Fri, 5 Jun 2026 14:18:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1780669131; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=m/2vtSOVVlfj9Agh7xSvbB4JlaTvw+8qJ6jd6ubSUFs=; b=twdh3Ycpj7sLpdtQLNHPHPVYHRUwWYN1ERYSFlfNpWLlvkLA0KIVdpLoe+MqfZC/jHHPEi 5SE6qz9q2Bvzo0cFjHwu6nSBqwAIGKnsT9bajMWc+7xmiGk/J0UXb99XLLwsr3D3/TSBGB J/SDEZQTpO9cTGYPpaFksAMMdoKOlEs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1780669131; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=m/2vtSOVVlfj9Agh7xSvbB4JlaTvw+8qJ6jd6ubSUFs=; b=aje03b7Tic9FXztzOMcuo43pteJhJBSxjuxEKffB7FLclGTddFvkuRMLl45UMwpOdWgC4h iEz7USw1rOPyxoBA== Authentication-Results: smtp-out1.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1780669130; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=m/2vtSOVVlfj9Agh7xSvbB4JlaTvw+8qJ6jd6ubSUFs=; b=bcgFYDsRcdd4pV0+YmhAxW/uDp5Zcs7qceR0wzqMJwd42pu3lPWjhVye3JBFczNNKRMtlr SvtwPECY1mW0JAOryguTiNqljlgj5a3SvO9dnAXlWKXTM1fdx7lVCA2YvPplLOU7MSVRJ+ W07L3Mm5GJByLf+7UCMMO/KfM6fRlfU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1780669130; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=m/2vtSOVVlfj9Agh7xSvbB4JlaTvw+8qJ6jd6ubSUFs=; b=0lw9JYz+L3a9x9UBe4lLhhiA+BVjxe5ZjhtALZqx7G20eElpexJpOeoySxzKsIT4sOZDN4 6AUznHoM01SKqzAw== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 969AF779A8; Fri, 5 Jun 2026 14:18:49 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 9ancGcnaImqhRAAAD6G6ig (envelope-from ); Fri, 05 Jun 2026 14:18:49 +0000 From: Fabiano Rosas To: Zide Chen , qemu-devel@nongnu.org, kvm@vger.kernel.org, Paolo Bonzini , Zhao Liu , Peter Xu , Sandipan Das Cc: Xiaoyao Li , Dongli Zhang , Dapeng Mi , Zide Chen Subject: Re: [PATCH v4 1/6] target/i386: Don't save/restore PERF_GLOBAL_OVF_CTRL MSRs In-Reply-To: <20260604025546.19378-2-zide.chen@intel.com> References: <20260604025546.19378-1-zide.chen@intel.com> <20260604025546.19378-2-zide.chen@intel.com> Date: Fri, 05 Jun 2026 11:18:47 -0300 Message-ID: <87ik7x6pfc.fsf@suse.de> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Spam-Flag: NO X-Spam-Score: -4.30 X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; MISSING_XM_UA(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_SEVEN(0.00)[11]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[amd.com:email,intel.com:email,oracle.com:email,suse.de:email,suse.de:mid,imap1.dmz-prg2.suse.org:helo] X-Spam-Level: Zide Chen writes: > From: Dapeng Mi > > MSR_CORE_PERF_GLOBAL_OVF_CTRL and MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR > are write-only MSRs and reads always return zero. > > Saving and restoring these MSRs is therefore unnecessary. Replace > VMSTATE_UINT64 with VMSTATE_UNUSED in the VMStateDescription to ignore > env.msr_global_ovf_ctrl during migration. This avoids the need to bump > version_id and does not introduce any migration incompatibility. > > Cc: Dongli Zhang > Cc: Sandipan Das > Fixes: e587632c228e ("target/i386/kvm: support perfmon-v2 for reset") > Signed-off-by: Dapeng Mi > Co-developed-by: Zide Chen > Signed-off-by: Zide Chen > --- > V3: > - Remove MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR as well. > --- > target/i386/cpu.h | 3 --- > target/i386/kvm/kvm.c | 10 ---------- > target/i386/machine.c | 4 ++-- > 3 files changed, 2 insertions(+), 15 deletions(-) > > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > index 6b500737c3be..ff44487d0b6d 100644 > --- a/target/i386/cpu.h > +++ b/target/i386/cpu.h > @@ -507,11 +507,9 @@ typedef enum X86Seg { > #define MSR_CORE_PERF_FIXED_CTR_CTRL 0x38d > #define MSR_CORE_PERF_GLOBAL_STATUS 0x38e > #define MSR_CORE_PERF_GLOBAL_CTRL 0x38f > -#define MSR_CORE_PERF_GLOBAL_OVF_CTRL 0x390 > > #define MSR_AMD64_PERF_CNTR_GLOBAL_STATUS 0xc0000300 > #define MSR_AMD64_PERF_CNTR_GLOBAL_CTL 0xc0000301 > -#define MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR 0xc0000302 > > #define MSR_K7_EVNTSEL0 0xc0010000 > #define MSR_K7_PERFCTR0 0xc0010004 > @@ -2104,7 +2102,6 @@ typedef struct CPUArchState { > uint64_t msr_fixed_ctr_ctrl; > uint64_t msr_global_ctrl; > uint64_t msr_global_status; > - uint64_t msr_global_ovf_ctrl; > uint64_t msr_fixed_counters[MAX_FIXED_COUNTERS]; > uint64_t msr_gp_counters[MAX_GP_COUNTERS]; > uint64_t msr_gp_evtsel[MAX_GP_COUNTERS]; > diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c > index a29f757c168a..1ac1803e8a2e 100644 > --- a/target/i386/kvm/kvm.c > +++ b/target/i386/kvm/kvm.c > @@ -4290,8 +4290,6 @@ static int kvm_put_msrs(X86CPU *cpu, KvmPutState level) > if (pmu_version > 1) { > kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_STATUS, > env->msr_global_status); > - kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_OVF_CTRL, > - env->msr_global_ovf_ctrl); Assuming there's no weird nested virtualization scenario and combination of migration, resets and context-switching between L1/L2 that implicitly relies on this (effective) clearing of the MSR to work properly. Reviewed-by: Fabiano Rosas