KVM: SVM: Remove TSS reloading code after VMEXIT

Remove the dedicated post-VMEXIT TSS reloading code now that KVM uses
VMLOAD to load host segment state, which includes TSS state.

Fixes: e79b91b ("KVM: SVM: use vmsave/vmload for saving/restoring additional host state")
Reported-by: Venkatesh Srinivas <venkateshs@google.com>
Suggested-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20230523165635.4002711-1-mizhang@google.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: mzhang3579

arch/x86/kvm/svm/svm.c

@@ -244,15 +244,6 @@ static u8 rsm_ins_bytes[] = "\x0f\xaa";
 
 static unsigned long iopm_base;
 
-struct kvm_ldttss_desc {
-	u16 limit0;
-	u16 base0;
-	unsigned base1:8, type:5, dpl:2, p:1;
-	unsigned limit1:4, zero0:3, g:1, base2:8;
-	u32 base3;
-	u32 zero1;
-} __attribute__((packed));
-
 DEFINE_PER_CPU(struct svm_cpu_data, svm_data);
 
 /*
@@ -588,7 +579,6 @@ static int svm_hardware_enable(void)
 
 	struct svm_cpu_data *sd;
 	uint64_t efer;
-	struct desc_struct *gdt;
 	int me = raw_smp_processor_id();
 
 	rdmsrl(MSR_EFER, efer);
@@ -601,9 +591,6 @@ static int svm_hardware_enable(void)
 	sd->next_asid = sd->max_asid + 1;
 	sd->min_asid = max_sev_asid + 1;
 
-	gdt = get_current_gdt_rw();
-	sd->tss_desc = (struct kvm_ldttss_desc *)(gdt + GDT_ENTRY_TSS);
-
 	wrmsrl(MSR_EFER, efer | EFER_SVME);
 
 	wrmsrl(MSR_VM_HSAVE_PA, sd->save_area_pa);
@@ -3457,14 +3444,6 @@ static int svm_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
 	return svm_invoke_exit_handler(vcpu, exit_code);
 }
 
-static void reload_tss(struct kvm_vcpu *vcpu)
-{
-	struct svm_cpu_data *sd = per_cpu_ptr(&svm_data, vcpu->cpu);
-
-	sd->tss_desc->type = 9; /* available 32/64-bit TSS */
-	load_TR_desc();
-}
-
 static void pre_svm_run(struct kvm_vcpu *vcpu)
 {
 	struct svm_cpu_data *sd = per_cpu_ptr(&svm_data, vcpu->cpu);
@@ -4099,9 +4078,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
 
 	svm_vcpu_enter_exit(vcpu, spec_ctrl_intercepted);
 
-	if (!sev_es_guest(vcpu->kvm))
-		reload_tss(vcpu);
-
 	if (!static_cpu_has(X86_FEATURE_V_SPEC_CTRL))
 		x86_spec_ctrl_restore_host(svm->virt_spec_ctrl);
 

arch/x86/kvm/svm/svm.h

@@ -303,7 +303,6 @@ struct svm_cpu_data {
 	u32 max_asid;
 	u32 next_asid;
 	u32 min_asid;
-	struct kvm_ldttss_desc *tss_desc;
 
 	struct page *save_area;
 	unsigned long save_area_pa;