xen: Allow PV-OPS kernel to detect whether XSAVE is supported (947ccf9c) · Commits · 戴 / test

Xen fails to mask XSAVE from the cpuid feature, despite not historically supporting guest use of XSAVE. However, now that XSAVE support has been added to Xen, we need to reliably detect its presence. The most reliable way to do this is to look at the OSXSAVE feature in cpuid which is set iff the OS (Xen, in this case), has set CR4.OSXSAVE. [ Cleaned up conditional a bit. - Jeremy ] Signed-off-by:

Shan Haitao <haitao.shan@intel.com> Signed-off-by:

Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by:

Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/enlighten.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -238,6 +238,7 @@ static void xen_cpuid(unsigned int ax, unsigned int bx,
		static __init void xen_init_cpuid_mask(void)
		{
		unsigned int ax, bx, cx, dx;
		unsigned int xsave_mask;

		cpuid_leaf1_edx_mask =
		~((1 << X86_FEATURE_MCE) \| /* disable MCE */
		@@ -249,8 +250,16 @@ static __init void xen_init_cpuid_mask(void)
		cpuid_leaf1_edx_mask &=
		~((1 << X86_FEATURE_APIC) \| /* disable local APIC */
		(1 << X86_FEATURE_ACPI)); /* disable ACPI */
		ax = 1;
		xen_cpuid(&ax, &bx, &cx, &dx);

		cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_XSAVE % 32)); /* disable XSAVE */
		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 */
		}

		static void xen_set_debugreg(int reg, unsigned long val)

Admin message