KVM: SVM: Move fs/gs/ldt save/restore to heavyweight exit path
ldt is never used in the kernel context; same goes for fs (x86_64) and gs
(i386). So save/restore them in the heavyweight exit path instead
of the lightweight path.
By itself, this doesn't buy us much, but it paves the way for moving vmload
and vmsave to the heavyweight exit path, since they modify the same registers.
[jan: fix copy/pase mistake on i386]
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a217978..8ea4a79 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -125,6 +125,9 @@
u64 host_user_msrs[NR_HOST_SAVE_USER_MSRS];
struct {
+ u16 fs;
+ u16 gs;
+ u16 ldt;
u64 gs_base;
} host;
@@ -184,6 +187,9 @@
static int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
bool has_error_code, u32 error_code);
+static void save_host_msrs(struct kvm_vcpu *vcpu);
+static void load_host_msrs(struct kvm_vcpu *vcpu);
+
static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
{
return container_of(vcpu, struct vcpu_svm, vcpu);
@@ -996,6 +1002,11 @@
svm->asid_generation = 0;
}
+ save_host_msrs(vcpu);
+ savesegment(fs, svm->host.fs);
+ savesegment(gs, svm->host.gs);
+ svm->host.ldt = kvm_read_ldt();
+
for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
rdmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
}
@@ -1006,6 +1017,14 @@
int i;
++vcpu->stat.host_state_reload;
+ kvm_load_ldt(svm->host.ldt);
+#ifdef CONFIG_X86_64
+ loadsegment(fs, svm->host.fs);
+ load_gs_index(svm->host.gs);
+ wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
+#else
+ loadsegment(gs, svm->host.gs);
+#endif
for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
}
@@ -3314,9 +3333,6 @@
static void svm_vcpu_run(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
- u16 fs_selector;
- u16 gs_selector;
- u16 ldt_selector;
svm->vmcb->save.rax = vcpu->arch.regs[VCPU_REGS_RAX];
svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP];
@@ -3333,10 +3349,6 @@
sync_lapic_to_cr8(vcpu);
- save_host_msrs(vcpu);
- savesegment(fs, fs_selector);
- savesegment(gs, gs_selector);
- ldt_selector = kvm_read_ldt();
svm->vmcb->save.cr2 = vcpu->arch.cr2;
clgi();
@@ -3415,13 +3427,8 @@
);
load_host_msrs(vcpu);
- kvm_load_ldt(ldt_selector);
- loadsegment(fs, fs_selector);
-#ifdef CONFIG_X86_64
- load_gs_index(gs_selector);
- wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
-#else
- loadsegment(gs, gs_selector);
+#ifndef CONFIG_X86_64
+ loadsegment(fs, svm->host.fs);
#endif
reload_tss(vcpu);
