Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 40f4ac0b authored by Juergen Gross's avatar Juergen Gross
Browse files

x86/xen: fix xsave capability setting 



Commit 690b7f10b4f9f ("x86/xen: use capabilities instead of fake cpuid
values for xsave") introduced a regression as it tried to make use of
the fixup feature before it being available.

Fall back to the old variant testing via cpuid().

Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
parent 3dbd8204

arch/x86/xen/enlighten_pv.c

+9 −23
Original line number Diff line number Diff line
@@ -277,26 +277,15 @@ static bool __init xen_check_mwait(void) 


static bool __init xen_check_xsave(void)

{

	unsigned int err, eax, edx;

	unsigned int cx, xsave_mask;



	/*

	 * 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));

	cx = cpuid_ecx(1);



	return err == 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 */

	return (cx & xsave_mask) == xsave_mask;

}



static void __init xen_init_capabilities(void)
@@ -317,10 +306,7 @@ static void __init xen_init_capabilities(void) 
	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 {

	if (!xen_check_xsave()) {

		setup_clear_cpu_cap(X86_FEATURE_XSAVE);

		setup_clear_cpu_cap(X86_FEATURE_OSXSAVE);

	}