From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755380AbdDRGcl (ORCPT ); Tue, 18 Apr 2017 02:32:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:39932 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754038AbdDRGb2 (ORCPT ); Tue, 18 Apr 2017 02:31:28 -0400 From: Juergen Gross To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org Cc: boris.ostrovsky@oracle.com, Juergen Gross Subject: [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Date: Tue, 18 Apr 2017 08:31:17 +0200 Message-Id: <20170418063119.11654-10-jgross@suse.com> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170418063119.11654-1-jgross@suse.com> References: <20170418063119.11654-1-jgross@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When running as pv domain xen_cpuid() is being used instead of native_cpuid(). In xen_cpuid() the xsave feature availability is indicated by special casing the related cpuid leaf. Instead of delivering fake cpuid values set or clear the cpu capability bits for xsave instead. Signed-off-by: Juergen Gross --- arch/x86/xen/enlighten_pv.c | 46 +++++++++++++++++++++++---------------------- 1 file changed, 24 insertions(+), 22 deletions(-) diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 38dec28a8e6d..e6bf71d76e10 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -165,8 +165,6 @@ xen_running_on_version_or_later(unsigned int major, unsigned int minor) return false; } -static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0; - static __read_mostly unsigned int cpuid_leaf5_ecx_val; static __read_mostly unsigned int cpuid_leaf5_edx_val; @@ -174,16 +172,12 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx, unsigned int *cx, unsigned int *dx) { unsigned maskebx = ~0; - unsigned maskecx = ~0; + /* * Mask out inconvenient features, to try and disable as many * unsupported kernel subsystems as possible. */ switch (*ax) { - case 1: - maskecx = cpuid_leaf1_ecx_mask; - break; - case CPUID_MWAIT_LEAF: /* Synthesize the values.. */ *ax = 0; @@ -206,7 +200,6 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx, : "0" (*ax), "2" (*cx)); *bx &= maskebx; - *cx &= maskecx; } STACK_FRAME_NON_STANDARD(xen_cpuid); /* XEN_EMULATE_PREFIX */ @@ -281,22 +274,24 @@ static bool __init xen_check_mwait(void) return false; #endif } -static void __init xen_init_cpuid_mask(void) + +static bool __init xen_check_xsave(void) { - unsigned int ax, bx, cx, dx; - unsigned int xsave_mask; + unsigned int err, eax, edx; - ax = 1; - cx = 0; - cpuid(1, &ax, &bx, &cx, &dx); + /* Test OSXSAVE capability via xgetbv instruction. */ + asm volatile("1: .byte 0x0f,0x01,0xd0\n\t" /* xgetbv */ + "xor %[err], %[err]\n" + "2:\n\t" + ".pushsection .fixup,\"ax\"\n\t" + "3: movl $1,%[err]\n\t" + "jmp 2b\n\t" + ".popsection\n\t" + _ASM_EXTABLE(1b, 3b) + : [err] "=r" (err), "=a" (eax), "=d" (edx) + : "c" (0)); - xsave_mask = - (1 << (X86_FEATURE_XSAVE % 32)) | - (1 << (X86_FEATURE_OSXSAVE % 32)); - - /* Xen will set CR4.OSXSAVE if supported and not disabled by force */ - if ((cx & xsave_mask) != xsave_mask) - cpuid_leaf1_ecx_mask &= ~xsave_mask; /* disable XSAVE & OSXSAVE */ + return err == 0; } static void __init xen_init_capabilities(void) @@ -316,6 +311,14 @@ static void __init xen_init_capabilities(void) setup_force_cpu_cap(X86_FEATURE_MWAIT); else setup_clear_cpu_cap(X86_FEATURE_MWAIT); + + if (xen_check_xsave()) { + setup_force_cpu_cap(X86_FEATURE_XSAVE); + setup_force_cpu_cap(X86_FEATURE_OSXSAVE); + } else { + setup_clear_cpu_cap(X86_FEATURE_XSAVE); + setup_clear_cpu_cap(X86_FEATURE_OSXSAVE); + } } static void xen_set_debugreg(int reg, unsigned long val) @@ -1308,7 +1311,6 @@ asmlinkage __visible void __init xen_start_kernel(void) xen_setup_gdt(0); xen_init_irq_ops(); - xen_init_cpuid_mask(); xen_init_capabilities(); #ifdef CONFIG_X86_LOCAL_APIC -- 2.12.0