From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 2F7AA1865 for ; Sun, 17 Mar 2024 08:32:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710664351; cv=none; b=ZG52z13jmccoMNTXMAkgRjn8ZZ+BDS3OV4GadWxAgCmEwMTSdaeYo6y8bZDvwYzkuNLwxhN8iLWWlgcnO/VzhA2Bt6Jj0OGmotOocbarNGCl/YpZBubtmSjR9LbUZOfhp7kYnCp2zE5/oJmSEyUH9uhr2OCaNOp0UJNXofbkAyA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710664351; c=relaxed/simple; bh=92hfYwokdeu/YuQ+PkV1vqiKNBjGzAAHo/vUwVuYsRo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iAy5yTVpgzc7Sal7p4McUTqNw93EwlLGwtKqbfQLC5QjAZRYy68OoqMVyTWRL/SGNsrhsG2STwFJNaD66gUmt8XQvgHizPZP1mc1z8MeYpj4L9Vc2Kq2sUIFdPLwmEhjKrW0p4tU9O1tQdYZSZ0TH3gmLK4ixqGByRHSUabNgSM= 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=C1AxQ1BI; arc=none smtp.client-ip=192.198.163.8 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="C1AxQ1BI" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1710664349; x=1742200349; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=92hfYwokdeu/YuQ+PkV1vqiKNBjGzAAHo/vUwVuYsRo=; b=C1AxQ1BIs/Y9SVmVSVFzEY9by7Opx+Im+9/OjnB1bBLBiRcUz3+lyv71 c+Kz0VTJ9jD/ezNge5nf5TOULAde1zVamwprFDQSFhzwAfFU6cCxzRzhN OcHO6365KWUWB5hcbVPkXwObxlsdR3CQ3XF1h2fofe0dz02/yJsBFT0o3 5g/QIoUTjLMOXUkaATOVe5U2KLzOmAyCMJwt1oj3XMDv3oSobnVfICAYw xf8B69sSovgLUgD/wra0tdUgsdHPmo0GiXCUwrJ8CcXHNMjRx0dzHICqi GMn4uS6o0MO24IUTMYwdQHcI9RliLSXodAwievDk1GowUoZdatFnwazvG g==; X-IronPort-AV: E=McAfee;i="6600,9927,11015"; a="23006648" X-IronPort-AV: E=Sophos;i="6.07,132,1708416000"; d="scan'208";a="23006648" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2024 01:32:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,132,1708416000"; d="scan'208";a="13788545" Received: from linux.bj.intel.com ([10.238.157.71]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2024 01:32:26 -0700 Date: Sun, 17 Mar 2024 16:29:31 +0800 From: Tao Su To: Gerd Hoffmann Cc: qemu-devel@nongnu.org, Tom Lendacky , Marcelo Tosatti , Paolo Bonzini , kvm@vger.kernel.org Subject: Re: [PATCH v3 2/3] kvm: add support for guest physical bits Message-ID: References: <20240313132719.939417-1-kraxel@redhat.com> <20240313132719.939417-3-kraxel@redhat.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 Content-Disposition: inline In-Reply-To: <20240313132719.939417-3-kraxel@redhat.com> On Wed, Mar 13, 2024 at 02:27:18PM +0100, Gerd Hoffmann wrote: > Query kvm for supported guest physical address bits, in cpuid > function 80000008, eax[23:16]. Usually this is identical to host > physical address bits. With NPT or EPT being used this might be > restricted to 48 (max 4-level paging address space size) even if > the host cpu supports more physical address bits. > > When set pass this to the guest, using cpuid too. Guest firmware > can use this to figure how big the usable guest physical address > space is, so PCI bar mapping are actually reachable. > > Signed-off-by: Gerd Hoffmann > --- > target/i386/cpu.h | 1 + > target/i386/cpu.c | 1 + > target/i386/kvm/kvm-cpu.c | 32 +++++++++++++++++++++++++++++++- > 3 files changed, 33 insertions(+), 1 deletion(-) > > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > index 952174bb6f52..d427218827f6 100644 > --- a/target/i386/cpu.h > +++ b/target/i386/cpu.h > @@ -2026,6 +2026,7 @@ struct ArchCPU { > > /* Number of physical address bits supported */ > uint32_t phys_bits; > + uint32_t guest_phys_bits; > > /* in order to simplify APIC support, we leave this pointer to the > user */ > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index 9a210d8d9290..c88c895a5b3e 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -6570,6 +6570,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count, > if (env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_LM) { > /* 64 bit processor */ > *eax |= (cpu_x86_virtual_addr_width(env) << 8); > + *eax |= (cpu->guest_phys_bits << 16); > } > *ebx = env->features[FEAT_8000_0008_EBX]; > if (cs->nr_cores * cs->nr_threads > 1) { > diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c > index 9c791b7b0520..a2b7bfaeadf8 100644 > --- a/target/i386/kvm/kvm-cpu.c > +++ b/target/i386/kvm/kvm-cpu.c > @@ -18,10 +18,36 @@ > #include "kvm_i386.h" > #include "hw/core/accel-cpu.h" > > +static void kvm_set_guest_phys_bits(CPUState *cs) > +{ > + X86CPU *cpu = X86_CPU(cs); > + uint32_t eax, guest_phys_bits; > + > + if (!cpu->host_phys_bits) { > + return; > + } > + > + eax = kvm_arch_get_supported_cpuid(cs->kvm_state, 0x80000008, 0, R_EAX); > + guest_phys_bits = (eax >> 16) & 0xff; > + if (!guest_phys_bits) { > + return; > + } > + > + if (cpu->guest_phys_bits == 0 || > + cpu->guest_phys_bits > guest_phys_bits) { > + cpu->guest_phys_bits = guest_phys_bits; > + } > + > + if (cpu->guest_phys_bits > cpu->host_phys_bits_limit) { > + cpu->guest_phys_bits = cpu->host_phys_bits_limit; host_phys_bits_limit is zero by default, so I think it is better to be like: if (cpu->host_phys_bits_limit && cpu->guest_phys_bits > cpu->host_phys_bits_limit) { cpu->guest_phys_bits = cpu->host_phys_bits_limit; } > + } > +} > + > static bool kvm_cpu_realizefn(CPUState *cs, Error **errp) > { > X86CPU *cpu = X86_CPU(cs); > CPUX86State *env = &cpu->env; > + bool ret; > > /* > * The realize order is important, since x86_cpu_realize() checks if > @@ -50,7 +76,11 @@ static bool kvm_cpu_realizefn(CPUState *cs, Error **errp) > MSR_IA32_UCODE_REV); > } > } > - return host_cpu_realizefn(cs, errp); > + ret = host_cpu_realizefn(cs, errp); > + > + kvm_set_guest_phys_bits(cs); > + > + return ret; > } > > static bool lmce_supported(void) > -- > 2.44.0 > >