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authorAndy Lutomirski <luto@kernel.org>2020-06-26 10:24:30 -0700
committerThomas Gleixner <tglx@linutronix.de>2020-07-01 15:27:20 +0200
commitd029bff60aa6c7eab281d52602b6a7a971615324 (patch)
treebc6aadea2b2a234361696aff4a6a9d2ac1564d36
parent40c45904f818c1f6555294ca27afc5fda4f09e68 (diff)
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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 <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/f07c08f178fe9711915862b656722a207cd52c28.1593192140.git.luto@kernel.org
-rw-r--r--arch/x86/kernel/process_64.c24
1 files changed, 18 insertions, 6 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index cb8e37d3acaa..e14476f0c533 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();
+ }
}
/*