mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-11-27 08:01:14 +00:00
86 lines
2.3 KiB
Diff
86 lines
2.3 KiB
Diff
--- a/arch/x86/xen/enlighten.c
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+++ b/arch/x86/xen/enlighten.c
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@@ -168,21 +168,23 @@ static void __init xen_banner(void)
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xen_feature(XENFEAT_mmu_pt_update_preserve_ad) ? " (preserve-AD)" : "");
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}
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+static __read_mostly unsigned int cpuid_leaf1_edx_mask = ~0;
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+static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0;
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+
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static void xen_cpuid(unsigned int *ax, unsigned int *bx,
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unsigned int *cx, unsigned int *dx)
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{
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+ unsigned maskecx = ~0;
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unsigned maskedx = ~0;
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/*
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* Mask out inconvenient features, to try and disable as many
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* unsupported kernel subsystems as possible.
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*/
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- if (*ax == 1)
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- maskedx = ~((1 << X86_FEATURE_APIC) | /* disable APIC */
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- (1 << X86_FEATURE_ACPI) | /* disable ACPI */
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- (1 << X86_FEATURE_MCE) | /* disable MCE */
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- (1 << X86_FEATURE_MCA) | /* disable MCA */
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- (1 << X86_FEATURE_ACC)); /* thermal monitoring */
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+ if (*ax == 1) {
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+ maskecx = cpuid_leaf1_ecx_mask;
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+ maskedx = cpuid_leaf1_edx_mask;
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+ }
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asm(XEN_EMULATE_PREFIX "cpuid"
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: "=a" (*ax),
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@@ -190,9 +192,43 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
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"=c" (*cx),
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"=d" (*dx)
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: "0" (*ax), "2" (*cx));
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+
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+ *cx &= maskecx;
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*dx &= maskedx;
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}
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+static __init void xen_init_cpuid_mask(void)
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+{
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+ unsigned int ax, bx, cx, dx;
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+
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+ cpuid_leaf1_edx_mask =
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+ ~((1 << X86_FEATURE_MCE) | /* disable MCE */
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+ (1 << X86_FEATURE_MCA) | /* disable MCA */
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+ (1 << X86_FEATURE_ACC)); /* thermal monitoring */
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+
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+ if (!xen_initial_domain())
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+ cpuid_leaf1_edx_mask &=
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+ ~((1 << X86_FEATURE_APIC) | /* disable local APIC */
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+ (1 << X86_FEATURE_ACPI)); /* disable ACPI */
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+
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+ ax = 1;
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+ xen_cpuid(&ax, &bx, &cx, &dx);
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+
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+ /* cpuid claims we support xsave; try enabling it to see what happens */
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+ if (cx & (1 << (X86_FEATURE_XSAVE % 32))) {
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+ unsigned long cr4;
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+
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+ set_in_cr4(X86_CR4_OSXSAVE);
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+
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+ cr4 = read_cr4();
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+
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+ if ((cr4 & X86_CR4_OSXSAVE) == 0)
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+ cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_XSAVE % 32));
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+
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+ clear_in_cr4(X86_CR4_OSXSAVE);
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+ }
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+}
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+
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static void xen_set_debugreg(int reg, unsigned long val)
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{
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HYPERVISOR_set_debugreg(reg, val);
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@@ -903,6 +939,8 @@ asmlinkage void __init xen_start_kernel(void)
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xen_init_irq_ops();
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+ xen_init_cpuid_mask();
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+
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#ifdef CONFIG_X86_LOCAL_APIC
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/*
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* set up the basic apic ops.
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