iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: vmx: refactor segmentation code in vmx_save_host_state()

Browse Source 
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: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2018-07-23 12:32:41 -07:00 committed by Paolo Bonzini
parent e49fcb8b9e
commit e368b875a8
1 changed files with 28 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
arch/x86/kvm/vmx.c
View File

@ -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,