Commit e368b875 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: vmx: refactor segmentation code in vmx_save_host_state() 

Use local variables in vmx_save_host_state() to temporarily track
the selector and base values for FS and GS, and reorganize the
code so that the 64-bit vs 32-bit portions are contained within
a single #ifdef.  This refactoring paves the way for future patches
to modify the updating of VMCS state with minimal changes to the
code, and (hopefully) simplifies resolving a likely conflict with
another in-flight patch[1] by being the whipping boy for future
patches.

[1] https://www.spinics.net/lists/kvm/msg171647.html



Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e49fcb8b

arch/x86/kvm/vmx.c

+28 −25
Original line number Diff line number Diff line
@@ -2662,8 +2662,9 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu) 
	struct vcpu_vmx *vmx = to_vmx(vcpu);

#ifdef CONFIG_X86_64

	int cpu = raw_smp_processor_id();

	unsigned long fs_base, kernel_gs_base;

#endif

	unsigned long fs_base, gs_base;

	u16 fs_sel, gs_sel;

	int i;



	if (vmx->host_state.loaded)
@@ -2678,49 +2679,51 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu) 
	vmx->host_state.gs_ldt_reload_needed = vmx->host_state.ldt_sel;



#ifdef CONFIG_X86_64

	savesegment(ds, vmx->host_state.ds_sel);

	savesegment(es, vmx->host_state.es_sel);



	gs_base = cpu_kernelmode_gs_base(cpu);

	if (likely(is_64bit_mm(current->mm))) {

		save_fsgs_for_kvm();

		vmx->host_state.fs_sel = current->thread.fsindex;

		vmx->host_state.gs_sel = current->thread.gsindex;

		fs_sel = current->thread.fsindex;

		gs_sel = current->thread.gsindex;

		fs_base = current->thread.fsbase;

		kernel_gs_base = current->thread.gsbase;

		vmx->msr_host_kernel_gs_base = current->thread.gsbase;

	} else {

#endif

		savesegment(fs, vmx->host_state.fs_sel);

		savesegment(gs, vmx->host_state.gs_sel);

#ifdef CONFIG_X86_64

		savesegment(fs, fs_sel);

		savesegment(gs, gs_sel);

		fs_base = read_msr(MSR_FS_BASE);

		kernel_gs_base = read_msr(MSR_KERNEL_GS_BASE);

		vmx->msr_host_kernel_gs_base = read_msr(MSR_KERNEL_GS_BASE);

	}



	if (is_long_mode(&vmx->vcpu))

		wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);

#else

	savesegment(fs, fs_sel);

	savesegment(gs, gs_sel);

	fs_base = segment_base(fs_sel);

	gs_base = segment_base(gs_sel);

#endif

	if (!(vmx->host_state.fs_sel & 7)) {

		vmcs_write16(HOST_FS_SELECTOR, vmx->host_state.fs_sel);



	vmx->host_state.fs_sel = fs_sel;

	if (!(fs_sel & 7)) {

		vmcs_write16(HOST_FS_SELECTOR, fs_sel);

		vmx->host_state.fs_reload_needed = 0;

	} else {

		vmcs_write16(HOST_FS_SELECTOR, 0);

		vmx->host_state.fs_reload_needed = 1;

	}

	if (!(vmx->host_state.gs_sel & 7))

		vmcs_write16(HOST_GS_SELECTOR, vmx->host_state.gs_sel);

	vmx->host_state.gs_sel = gs_sel;

	if (!(gs_sel & 7))

		vmcs_write16(HOST_GS_SELECTOR, gs_sel);

	else {

		vmcs_write16(HOST_GS_SELECTOR, 0);

		vmx->host_state.gs_ldt_reload_needed = 1;

	}



#ifdef CONFIG_X86_64

	savesegment(ds, vmx->host_state.ds_sel);

	savesegment(es, vmx->host_state.es_sel);



	vmcs_writel(HOST_FS_BASE, fs_base);

	vmcs_writel(HOST_GS_BASE, cpu_kernelmode_gs_base(cpu));

	vmcs_writel(HOST_GS_BASE, gs_base);



	vmx->msr_host_kernel_gs_base = kernel_gs_base;

	if (is_long_mode(&vmx->vcpu))

		wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);

#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));

#endif

	for (i = 0; i < vmx->save_nmsrs; ++i)

		kvm_set_shared_msr(vmx->guest_msrs[i].index,

				   vmx->guest_msrs[i].data,

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