Commit d029bff6 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Thomas Gleixner
Browse files

x86/fsgsbase: Fix Xen PV support 



On Xen PV, SWAPGS doesn't work.  Teach __rdfsbase_inactive() and
__wrgsbase_inactive() to use rdmsrl()/wrmsrl() on Xen PV.  The Xen
pvop code will understand this and issue the correct hypercalls.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/f07c08f178fe9711915862b656722a207cd52c28.1593192140.git.luto@kernel.org
parent 40c45904

arch/x86/kernel/process_64.c

+18 −6
Original line number Diff line number Diff line
@@ -163,9 +163,15 @@ static noinstr unsigned long __rdgsbase_inactive(void) 


	lockdep_assert_irqs_disabled();



	if (!static_cpu_has(X86_FEATURE_XENPV)) {

		native_swapgs();

		gsbase = rdgsbase();

		native_swapgs();

	} else {

		instrumentation_begin();

		rdmsrl(MSR_KERNEL_GS_BASE, gsbase);

		instrumentation_end();

	}



	return gsbase;

}
@@ -182,9 +188,15 @@ static noinstr void __wrgsbase_inactive(unsigned long gsbase) 
{

	lockdep_assert_irqs_disabled();



	if (!static_cpu_has(X86_FEATURE_XENPV)) {

		native_swapgs();

		wrgsbase(gsbase);

		native_swapgs();

	} else {

		instrumentation_begin();

		wrmsrl(MSR_KERNEL_GS_BASE, gsbase);

		instrumentation_end();

	}

}



/*