vmx_save_host_state() is only called from kvm_arch_vcpu_ioctl_run() so
the context is pretty well defined and as we're past 'swapgs' MSR_GS_BASE
should contain kernel's GS base which we point to irq_stack_union.
irq_stack_union needs to be exported as KVM can be a module.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/kernel/cpu/common.c | 1 +
arch/x86/kvm/vmx.c | 3 ++-
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 348cf4821240..057393711093 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1398,6 +1398,7 @@ __setup("clearcpuid=", setup_clearcpuid);
#ifdef CONFIG_X86_64
DEFINE_PER_CPU_FIRST(union irq_stack_union,
irq_stack_union) __aligned(PAGE_SIZE) __visible;
+EXPORT_PER_CPU_SYMBOL(irq_stack_union);
/*
* The following percpu variables are hot. Align current_task to
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5be34d13d88f..bf856b7ece3f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2158,7 +2158,8 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu)
#ifdef CONFIG_X86_64
vmcs_writel(HOST_FS_BASE, current->thread.fsbase);
- vmcs_writel(HOST_GS_BASE, read_msr(MSR_GS_BASE));
+ vmcs_writel(HOST_GS_BASE, (unsigned long)
+ per_cpu(irq_stack_union.gs_base, smp_processor_id()));
#else
vmcs_writel(HOST_FS_BASE, segment_base(vmx->host_state.fs_sel));
vmcs_writel(HOST_GS_BASE, segment_base(vmx->host_state.gs_sel));
--
2.14.3
