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| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2018-03-13 18:48:04 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2018-03-16 22:03:53 +0100 |
| commit | 42b933b59721f288e3ce23ca79a17a973808dab9 (patch) | |
| tree | 24f455d30d65833ac4eb2d00a2029f09519aa5aa /arch/x86/kernel/process_64.c | |
| parent | b31c114b82b2b55913d2cf744e6a665c2ca090ac (diff) | |
| download | linux-42b933b59721f288e3ce23ca79a17a973808dab9.tar.bz2 | |
x86/kvm/vmx: read MSR_{FS,KERNEL_GS}_BASE from current->thread
vmx_save_host_state() is only called from kvm_arch_vcpu_ioctl_run() so
the context is pretty well defined. Read MSR_{FS,KERNEL_GS}_BASE from
current->thread after calling save_fsgs() which takes care of
X86_BUG_NULL_SEG case now and will do RD[FG,GS]BASE when FSGSBASE
extensions are exposed to userspace (currently they are not).
Acked-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kernel/process_64.c')
| -rw-r--r-- | arch/x86/kernel/process_64.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 9eb448c7859d..4b100fe0f508 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -205,6 +205,20 @@ static __always_inline void save_fsgs(struct task_struct *task) save_base_legacy(task, task->thread.gsindex, GS); } +#if IS_ENABLED(CONFIG_KVM) +/* + * While a process is running,current->thread.fsbase and current->thread.gsbase + * may not match the corresponding CPU registers (see save_base_legacy()). KVM + * wants an efficient way to save and restore FSBASE and GSBASE. + * When FSGSBASE extensions are enabled, this will have to use RD{FS,GS}BASE. + */ +void save_fsgs_for_kvm(void) +{ + save_fsgs(current); +} +EXPORT_SYMBOL_GPL(save_fsgs_for_kvm); +#endif + static __always_inline void loadseg(enum which_selector which, unsigned short sel) { |