From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 94E2239FCD7; Thu, 5 Mar 2026 11:59:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772711979; cv=none; b=sjm5xbJ/LTRQalaDnR/tarifub9WHLgnpO+ZsyHBfHEcbQSon6BGQHT1MOw51dbVYN3dUS9LW1iBBdBObnsvuAek48RcQL/xta6lsXc5E7BwAw/PSrTmYjkWq1d2jDR5BFucYj7ItcNb+FF5gtAwaKLc3kpJCtyDLhjyH6i8ADQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772711979; c=relaxed/simple; bh=AeuXgiCx7xhzsVKDGuFejcM03y0yG23W3D4Rt2mBXDU=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=Sg2J0KB9FYuKqGxTvxNPXQmO0ronHkkrM+vJHy1yP3nm2ceRbKwt/FaMabOcvn0CzjA5dZxJ31p6WHW1NZ8fw11I/N2moIETUvjrtQ/V0J0DYxS4jJLAMKWqT6g34mMcLye1pzgtbg3tTOhrAK87xkEUmQbxUdgtw2yqccK7aG8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=as8BJQ5w; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="as8BJQ5w" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44794C116C6; Thu, 5 Mar 2026 11:59:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772711979; bh=AeuXgiCx7xhzsVKDGuFejcM03y0yG23W3D4Rt2mBXDU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=as8BJQ5wx4ebZV/oAkMksNHMve+NNvCg1kzayGpoRtQ+NpIb/4xKTOF/z+RrOeEMd 4yNmRPwokwh8AvFFbbQ5D3vcYP1fom3MZLYIqxK8xPLuqQwfMmXh8JMG8ivcSKs6SR q4VzPrsxrUHAYD+/tGEuJbuWrPt7TMKWJEWvx7axuf4cMfqjIe0IxIKJVqlMnzBzQI KTxNczhCQAWPxaCAQK0ci3e+nkHJT56YlzVkjCeXxSIRGf77JfAMECXEUuUH5pOP9+ yqkuOxFF0oLu2YOBLVxCULDCvnlWdXUrHQ1ar8+1V2P/kTiJ1OXSwOCQ6UcdTZJUa+ dRGIs8GkhosEA== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vy7Me-0000000GQZ1-3Ib5; Thu, 05 Mar 2026 11:59:36 +0000 Date: Thu, 05 Mar 2026 11:59:36 +0000 Message-ID: <86pl5i7ahj.wl-maz@kernel.org> From: Marc Zyngier To: James Clark Cc: Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Colton Lewis , Alexandru Elisei , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: arm64: Read PMUVer as unsigned In-Reply-To: <20260305-james-kvm-pmuver-sign-v1-1-eea0a2116dd0@linaro.org> References: <20260305-james-kvm-pmuver-sign-v1-1-eea0a2116dd0@linaro.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/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: james.clark@linaro.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, coltonlewis@google.com, alexandru.elisei@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Thu, 05 Mar 2026 11:50:01 +0000, James Clark wrote: > > ID_AA64DFR0_EL1.PMUVer is an unsigned field, so this skips > initialization of host_data_ptr(nr_event_counters) for PMUv3 for Armv8.8 > onwards as they appear as negative values. > > Fix it by reading it as unsigned. > > Fixes: 2417218f2f23 ("KVM: arm64: Get rid of __kvm_get_mdcr_el2() and related warts") > Signed-off-by: James Clark > --- > arch/arm64/kvm/debug.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c > index 3ad6b7c6e4ba..b8632edba9a3 100644 > --- a/arch/arm64/kvm/debug.c > +++ b/arch/arm64/kvm/debug.c > @@ -76,7 +76,7 @@ void kvm_init_host_debug_data(void) > { > u64 dfr0 = read_sysreg(id_aa64dfr0_el1); > > - if (cpuid_feature_extract_signed_field(dfr0, ID_AA64DFR0_EL1_PMUVer_SHIFT) > 0) > + if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_PMUVer_SHIFT) > 0) > *host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N, > read_sysreg(pmcr_el0)); > How does this work on a system that advertises a non-architected PMU? M. -- Without deviation from the norm, progress is not possible.