From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zero.eik.bme.hu (zero.eik.bme.hu [152.66.115.2]) (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 972273101B0 for ; Tue, 4 Aug 2026 20:03:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=152.66.115.2 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785873794; cv=none; b=hiTYt+PtFc0QWOlfbNauwWrrjDiI6Nr36JE7Lu+fcAlvdJ+nY5gVq0p3OPj8VkwOJNhNlPCvMG8HlS58PBPEd82ahH45GqJS3yXri3i5f/MekCIjT1W+i4PWMguB17mXU4Qe4qFmnxkNE5GAqtLKJLMBwin97y7omXdo2CxNFNg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785873794; c=relaxed/simple; bh=UdD9fFmhQXL0ARFmuX6dv7VMhE50mDsrNG0Ru1N6iJA=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=HAnvFz2Fk0Gb9Xrqss+D9wK8vBpHvas+b8Vu75EOHl/UIM5HESIVZyJ4m4gxMFXbbVZwnjEYZsz8tidXI5Uko0NvHHT7P2wIL1r8bleeBcITL+e5tCzoIwgBJM+NVei9O19qrhlBV9VM5LOCpg9i7BYY1IArGOJ/jBYQNeFsPMw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=eik.bme.hu; spf=pass smtp.mailfrom=eik.bme.hu; arc=none smtp.client-ip=152.66.115.2 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=eik.bme.hu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=eik.bme.hu Received: from localhost (localhost [127.0.0.1]) by zero.eik.bme.hu (Postfix) with ESMTP id 2C1EB583781; Tue, 04 Aug 2026 21:55:28 +0200 (CEST) X-Virus-Scanned: amavis at eik.bme.hu Received: from zero.eik.bme.hu ([127.0.0.1]) by localhost (zero.eik.bme.hu [127.0.0.1]) (amavis, port 10028) with ESMTP id 638yrKVN5oFT; Tue, 4 Aug 2026 21:55:26 +0200 (CEST) Received: by zero.eik.bme.hu (Postfix, from userid 432) id 11FA9583224; Tue, 04 Aug 2026 21:55:26 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by zero.eik.bme.hu (Postfix) with ESMTP id 10021583223; Tue, 04 Aug 2026 21:55:26 +0200 (CEST) Date: Tue, 4 Aug 2026 21:55:26 +0200 (CEST) From: BALATON Zoltan To: Amit Machhiwal cc: qemu-ppc@nongnu.org, Harsh Prateek Bora , Vaibhav Jain , Nicholas Piggin , Chinmay Rath , Glenn Miles , Paolo Bonzini , kvm@vger.kernel.org, qemu-devel@nongnu.org, Gautam Menghani Subject: Re: [PATCH v5 3/3] target/ppc/kvm: Use host compatibility mode for nested guests In-Reply-To: <20260804182914.83091-4-amachhiw@linux.ibm.com> Message-ID: References: <20260804182914.83091-1-amachhiw@linux.ibm.com> <20260804182914.83091-4-amachhiw@linux.ibm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed On Tue, 4 Aug 2026, Amit Machhiwal wrote: > On POWER systems, the host CPU may run in a compatibility mode (e.g., > a Power11 processor operating in Power10 compatibility mode). When > running nested KVM guests, QEMU currently derives the host CPU type > using mfpvr(), which reflects the physical processor version. This can > result in a mismatch between the CPU model used by QEMU and the > compatibility mode enforced by the host, leading to guest boot failures > such as "KVM-NESTEDv2: couldn't set guest wide elements". > > Update kvm_ppc_get_host_cpu_class() to check if the host is running in > a compatibility mode using kvm_ppc_host_compat_pvr(). When available, > use the compatibility PVR instead of the raw hardware PVR when selecting > the CPU model. This ensures that QEMU selects a CPU model consistent > with the host compatibility mode, allowing nested guests to boot > correctly. > > The guard uses #if defined(TARGET_PPC64) to prevent build breakage on > ppc32 targets where the POWER9/10/11 PVR constants are not defined. > > Tested-by: Gautam Menghani > Reviewed-by: Gautam Menghani > Signed-off-by: Amit Machhiwal > --- > No changes in this version. > > target/ppc/kvm.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > index d4c5601a00c4..aa8269186a1a 100644 > --- a/target/ppc/kvm.c > +++ b/target/ppc/kvm.c > @@ -2682,6 +2682,18 @@ PowerPCCPUClass *kvm_ppc_get_host_cpu_class(void) > uint32_t host_pvr = mfpvr(); > PowerPCCPUClass *pvr_pcc; > > +#if defined(TARGET_PPC64) > +#ifndef CONFIG_KVM > +#error "CONFIG_KVM is not enabled" > +#endif In meson.build: ppc_system_ss.add(when: 'CONFIG_KVM', if_true: files('kvm.c')) so I think this check and #error does not make sense. Regards, BALATON Zoltan > + uint32_t compat_host_pvr; > + > + compat_host_pvr = kvm_ppc_host_compat_pvr(); > + if (compat_host_pvr) { > + host_pvr = compat_host_pvr; > + } > +#endif /* TARGET_PPC64 */ > + > pvr_pcc = ppc_cpu_class_by_pvr(host_pvr); > if (pvr_pcc == NULL) { > pvr_pcc = ppc_cpu_class_by_pvr_mask(host_pvr); >