Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757277Ab0LBGcO (ORCPT ); Thu, 2 Dec 2010 01:32:14 -0500 Received: from mga02.intel.com ([134.134.136.20]:44256 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753944Ab0LBGcM (ORCPT ); Thu, 2 Dec 2010 01:32:12 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.59,286,1288594800"; d="scan'208";a="579753216" From: Sheng Yang Organization: Intel Opensource Technology Center To: Jeremy Fitzhardinge Subject: Re: [PATCH] xen: HVM X2APIC support Date: Thu, 2 Dec 2010 14:33:46 +0800 User-Agent: KMail/1.13.5 (Linux/2.6.35-22-generic; KDE/4.5.1; x86_64; ; ) Cc: Keir Fraser , "xen-devel" , linux-kernel@vger.kernel.org, Stefano Stabellini References: <1291258990-16080-1-git-send-email-sheng@linux.intel.com> <4CF73C80.4000101@goop.org> In-Reply-To: <4CF73C80.4000101@goop.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <201012021433.46976.sheng@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4597 Lines: 154 On Thursday 02 December 2010 14:28:16 Jeremy Fitzhardinge wrote: > On 12/01/2010 07:03 PM, Sheng Yang wrote: > > This patch is similiar to Gleb Natapov's patch for KVM, which enable the > > hypervisor to emulate x2apic feature for the guest. By this way, the > > emulation of lapic would be simpler with x2apic interface(MSR), and > > faster. > > We have a set of patches to directly use event channels from within hvm > domains, completely bypassing the apic altogether. Do we need this as > well? This is for other HVMs. And the pvhvm still have limitation like it can't use MSI/MSI-X assigned device. > > > Signed-off-by: Sheng Yang > > --- > > > > arch/x86/include/asm/xen/hypervisor.h | 33 > > +++++++++++++++++++++++++++++++++ arch/x86/kernel/apic/apic.c > > | 4 +++- > > arch/x86/xen/enlighten.c | 19 ------------------- > > 3 files changed, 36 insertions(+), 20 deletions(-) > > > > diff --git a/arch/x86/include/asm/xen/hypervisor.h > > b/arch/x86/include/asm/xen/hypervisor.h index 396ff4c..e862874 100644 > > --- a/arch/x86/include/asm/xen/hypervisor.h > > +++ b/arch/x86/include/asm/xen/hypervisor.h > > @@ -37,4 +37,37 @@ > > > > extern struct shared_info *HYPERVISOR_shared_info; > > extern struct start_info *xen_start_info; > > > > +#include > > + > > +static inline uint32_t xen_cpuid_base(void) > > +{ > > + uint32_t base, eax, ebx, ecx, edx; > > + char signature[13]; > > + > > + for (base = 0x40000000; base < 0x40010000; base += 0x100) { > > + cpuid(base, &eax, &ebx, &ecx, &edx); > > + *(uint32_t *)(signature + 0) = ebx; > > + *(uint32_t *)(signature + 4) = ecx; > > + *(uint32_t *)(signature + 8) = edx; > > + signature[12] = 0; > > + > > + if (!strcmp("XenVMMXenVMM", signature) && ((eax - base) >= 2)) > > + return base; > > + } > > + > > + return 0; > > +} > > + > > +#ifdef CONFIG_XEN > > +static inline bool xen_para_available(void) > > +{ > > + return 0; > > +} > > +#else > > +static inline bool xen_para_available(void) > > +{ > > + return (xen_cpuid_base() != 0); > > +} > > +#endif > > So this returns true if you're running a kernel without CONFIG_XEN under > Xen? Does that assume that all versions of Xen implement x2apic > emulation? Why wouldn't we also want this for CONFIG_XEN kernels? Because only the ones that implement the feature would expose x2apic CPUID. For CONFIG_XEN(pv or pvhvm), they both use evtchn, so no need for x2apic. -- regards Yang, Sheng > > J > > > + > > > > #endif /* _ASM_X86_XEN_HYPERVISOR_H */ > > > > diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c > > index 3f838d5..1b68221 100644 > > --- a/arch/x86/kernel/apic/apic.c > > +++ b/arch/x86/kernel/apic/apic.c > > @@ -52,6 +52,7 @@ > > > > #include > > #include > > #include > > > > +#include > > > > unsigned int num_processors; > > > > @@ -1476,7 +1477,8 @@ void __init enable_IR_x2apic(void) > > > > /* IR is required if there is APIC ID > 255 even when running > > > > * under KVM > > */ > > > > - if (max_physical_apicid > 255 || !kvm_para_available()) > > + if (max_physical_apicid > 255 || > > + (!kvm_para_available() && !xen_para_available())) > > > > goto nox2apic; > > > > /* > > > > * without IR all CPUs can be addressed by IOAPIC/MSI > > > > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > > index 235c0f4..819c365 100644 > > --- a/arch/x86/xen/enlighten.c > > +++ b/arch/x86/xen/enlighten.c > > @@ -1245,25 +1245,6 @@ asmlinkage void __init xen_start_kernel(void) > > > > #endif > > } > > > > -static uint32_t xen_cpuid_base(void) > > -{ > > - uint32_t base, eax, ebx, ecx, edx; > > - char signature[13]; > > - > > - for (base = 0x40000000; base < 0x40010000; base += 0x100) { > > - cpuid(base, &eax, &ebx, &ecx, &edx); > > - *(uint32_t *)(signature + 0) = ebx; > > - *(uint32_t *)(signature + 4) = ecx; > > - *(uint32_t *)(signature + 8) = edx; > > - signature[12] = 0; > > - > > - if (!strcmp("XenVMMXenVMM", signature) && ((eax - base) >= 2)) > > - return base; > > - } > > - > > - return 0; > > -} > > - > > > > static int init_hvm_pv_info(int *major, int *minor) > > { > > > > uint32_t eax, ebx, ecx, edx, pages, msr, base; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/