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.
Add new kernelmode_gs_base() API, irq_stack_union needs to be exported
as KVM can be build as module.
Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/include/asm/processor.h | 5 +++++
arch/x86/kernel/cpu/common.c | 3 ++-
arch/x86/kvm/vmx.c | 3 ++-
3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 1d816a3325a1..4fa4206029e3 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -407,6 +407,11 @@ union irq_stack_union {
DECLARE_PER_CPU_FIRST(union irq_stack_union, irq_stack_union) __visible;
DECLARE_INIT_PER_CPU(irq_stack_union);
+static inline unsigned long cpu_kernelmode_gs_base(int cpu)
+{
+ return (unsigned long)per_cpu(irq_stack_union.gs_base, cpu);
+}
+
DECLARE_PER_CPU(char *, irq_stack_ptr);
DECLARE_PER_CPU(unsigned int, irq_count);
extern asmlinkage void ignore_sysret(void);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 348cf4821240..4702fbd98f92 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -487,7 +487,7 @@ void load_percpu_segment(int cpu)
loadsegment(fs, __KERNEL_PERCPU);
#else
__loadsegment_simple(gs, 0);
- wrmsrl(MSR_GS_BASE, (unsigned long)per_cpu(irq_stack_union.gs_base, cpu));
+ wrmsrl(MSR_GS_BASE, cpu_kernelmode_gs_base(cpu));
#endif
load_stack_canary_segment();
}
@@ -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_GPL(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 189a347f3952..49953e362e92 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2123,6 +2123,7 @@ static unsigned long segment_base(u16 selector)
static void vmx_save_host_state(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ int cpu = raw_smp_processor_id();
int i;
if (vmx->host_state.loaded)
@@ -2165,7 +2166,7 @@ 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, cpu_kernelmode_gs_base(cpu));
#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
