x86/xen: use capabilities instead of fake cpuid values for xsave (6807cf65) · Commits · 戴 / test

arch/x86/xen/enlighten_pv.c

+30 −23

Original line number	Diff line number	Diff line
		@@ -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 +274,29 @@ static bool __init xen_check_mwait(void)
		return false;
		#endif
		}
		static void __init xen_init_cpuid_mask(void)
		{
		unsigned int ax, bx, cx, dx;
		unsigned int xsave_mask;

		ax = 1;
		cx = 0;
		cpuid(1, &ax, &bx, &cx, &dx);
		static bool __init xen_check_xsave(void)
		{
		unsigned int err, eax, edx;

		xsave_mask =
		(1 << (X86_FEATURE_XSAVE % 32)) \|
		(1 << (X86_FEATURE_OSXSAVE % 32));
		/*
		* Xen 4.0 and older accidentally leaked the host XSAVE flag into guest
		* view, despite not being able to support guests using the
		* functionality. Probe for the actual availability of XSAVE by seeing
		* whether xgetbv executes successfully or raises #UD.
		*/
		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));

		/* 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 +316,14 @@ 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 +1316,6 @@ 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

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