The following commit has been merged into the x86/fsgsbase branch of tip: Commit-ID: d029bff60aa6c7eab281d52602b6a7a971615324 Gitweb: https://git.kernel.org/tip/d029bff60aa6c7eab281d52602b6a7a971615324 Author: Andy Lutomirski <[email protected]> AuthorDate: Fri, 26 Jun 2020 10:24:30 -07:00 Committer: Thomas Gleixner <[email protected]> CommitterDate: Wed, 01 Jul 2020 15:27:20 +02:00
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: Andy Lutomirski <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Link: https://lkml.kernel.org/r/f07c08f178fe9711915862b656722a207cd52c28.1593192140.git.l...@kernel.org --- arch/x86/kernel/process_64.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index cb8e37d..e14476f 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -163,9 +163,15 @@ static noinstr unsigned long __rdgsbase_inactive(void) lockdep_assert_irqs_disabled(); - native_swapgs(); - gsbase = rdgsbase(); - native_swapgs(); + 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(); - native_swapgs(); - wrgsbase(gsbase); - native_swapgs(); + if (!static_cpu_has(X86_FEATURE_XENPV)) { + native_swapgs(); + wrgsbase(gsbase); + native_swapgs(); + } else { + instrumentation_begin(); + wrmsrl(MSR_KERNEL_GS_BASE, gsbase); + instrumentation_end(); + } } /*
