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Subject[PATCH V2 1/3] KVM: VMX: Save HOST_CR3 in vmx_prepare_switch_to_guest()
Date
From: Lai Jiangshan <laijs@linux.alibaba.com>

The host CR3 in the vcpu thread can only be changed when scheduling.

So HOST_CR3 can be saved only in vmx_prepare_switch_to_guest() and be
synced in vmx_sync_vmcs_host_state() when switching VMCS.

vmx_set_host_fs_gs() is called in both places, so it is renamed to
vmx_set_vmcs_host_state() and it also updates the HOST_CR3.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/kvm/vmx/nested.c | 11 +++--------
arch/x86/kvm/vmx/vmx.c | 21 +++++++++++----------
arch/x86/kvm/vmx/vmx.h | 5 +++--
3 files changed, 17 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 26b236187850..d07a7fa75783 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -245,7 +245,8 @@ static void vmx_sync_vmcs_host_state(struct vcpu_vmx *vmx,
src = &prev->host_state;
dest = &vmx->loaded_vmcs->host_state;

- vmx_set_host_fs_gs(dest, src->fs_sel, src->gs_sel, src->fs_base, src->gs_base);
+ vmx_set_vmcs_host_state(dest, src->cr3, src->fs_sel, src->gs_sel,
+ src->fs_base, src->gs_base);
dest->ldt_sel = src->ldt_sel;
#ifdef CONFIG_X86_64
dest->ds_sel = src->ds_sel;
@@ -3054,7 +3055,7 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- unsigned long cr3, cr4;
+ unsigned long cr4;
bool vm_fail;

if (!nested_early_check)
@@ -3077,12 +3078,6 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
*/
vmcs_writel(GUEST_RFLAGS, 0);

- cr3 = __get_current_cr3_fast();
- if (unlikely(cr3 != vmx->loaded_vmcs->host_state.cr3)) {
- vmcs_writel(HOST_CR3, cr3);
- vmx->loaded_vmcs->host_state.cr3 = cr3;
- }
-
cr4 = cr4_read_shadow();
if (unlikely(cr4 != vmx->loaded_vmcs->host_state.cr4)) {
vmcs_writel(HOST_CR4, cr4);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 7826556b2a47..5f281f5ee961 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1069,9 +1069,14 @@ static void pt_guest_exit(struct vcpu_vmx *vmx)
wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl);
}

-void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel,
- unsigned long fs_base, unsigned long gs_base)
+void vmx_set_vmcs_host_state(struct vmcs_host_state *host, unsigned long cr3,
+ u16 fs_sel, u16 gs_sel,
+ unsigned long fs_base, unsigned long gs_base)
{
+ if (unlikely(cr3 != host->cr3)) {
+ vmcs_writel(HOST_CR3, cr3);
+ host->cr3 = cr3;
+ }
if (unlikely(fs_sel != host->fs_sel)) {
if (!(fs_sel & 7))
vmcs_write16(HOST_FS_SELECTOR, fs_sel);
@@ -1166,7 +1171,9 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
gs_base = segment_base(gs_sel);
#endif

- vmx_set_host_fs_gs(host_state, fs_sel, gs_sel, fs_base, gs_base);
+ vmx_set_vmcs_host_state(host_state, __get_current_cr3_fast(),
+ fs_sel, gs_sel, fs_base, gs_base);
+
vmx->guest_state_loaded = true;
}

@@ -6629,7 +6636,7 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- unsigned long cr3, cr4;
+ unsigned long cr4;

/* Record the guest's net vcpu time for enforced NMI injections. */
if (unlikely(!enable_vnmi &&
@@ -6674,12 +6681,6 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
vmcs_writel(GUEST_RIP, vcpu->arch.regs[VCPU_REGS_RIP]);
vcpu->arch.regs_dirty = 0;

- cr3 = __get_current_cr3_fast();
- if (unlikely(cr3 != vmx->loaded_vmcs->host_state.cr3)) {
- vmcs_writel(HOST_CR3, cr3);
- vmx->loaded_vmcs->host_state.cr3 = cr3;
- }
-
cr4 = cr4_read_shadow();
if (unlikely(cr4 != vmx->loaded_vmcs->host_state.cr4)) {
vmcs_writel(HOST_CR4, cr4);
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 99588aa8474b..acb874db02da 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -374,8 +374,9 @@ int allocate_vpid(void);
void free_vpid(int vpid);
void vmx_set_constant_host_state(struct vcpu_vmx *vmx);
void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu);
-void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel,
- unsigned long fs_base, unsigned long gs_base);
+void vmx_set_vmcs_host_state(struct vmcs_host_state *host, unsigned long cr3,
+ u16 fs_sel, u16 gs_sel,
+ unsigned long fs_base, unsigned long gs_base);
int vmx_get_cpl(struct kvm_vcpu *vcpu);
bool vmx_emulation_required(struct kvm_vcpu *vcpu);
unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu);
--
2.19.1.6.gb485710b
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