Make host_state a property of a loaded_vmcs so that it can be
used as a cache of the VMCS fields, e.g. to lazily VMWRITE the
corresponding VMCS field. Treating host_state as a cache does
not work if it's not VMCS specific as the cache would become
incoherent when switching between vmcs01 and vmcs02.
Move vmcs_host_cr3 and vmcs_host_cr4 into host_state.
Explicitly zero out host_state when allocating a new VMCS for a
loaded_vmcs. Unlike the pre-existing vmcs_host_cr{3,4} usage,
the segment information is not guaranteed to be (re)initialized
when running a new nested VMCS, e.g. HOST_FS_BASE is not written
in vmx_set_constant_host_state().
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/vmx.c | 72 ++++++++++++++++++++++++++++------------------
1 file changed, 44 insertions(+), 28 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 2f070f192906..c66fcb01f355 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -204,6 +204,21 @@ struct vmcs {
char data[0];
};
+/*
+ * vmcs_host_state tracks registers that are loaded from the VMCS on VMEXIT
+ * and whose values change infrequently, but are not consant. I.e. this is
+ * used as a write-through cache of the corresponding VMCS fields.
+ */
+struct vmcs_host_state {
+ unsigned long cr3; /* May not match real cr3 */
+ unsigned long cr4; /* May not match real cr4 */
+
+ u16 fs_sel, gs_sel, ldt_sel;
+#ifdef CONFIG_X86_64
+ u16 ds_sel, es_sel;
+#endif
+};
+
/*
* Track a VMCS that may be loaded on a certain CPU. If it is (cpu!=-1), also
* remember whether it was VMLAUNCHed, and maintain a linked list of all VMCSs
@@ -215,14 +230,13 @@ struct loaded_vmcs {
int cpu;
bool launched;
bool nmi_known_unmasked;
- unsigned long vmcs_host_cr3; /* May not match real cr3 */
- unsigned long vmcs_host_cr4; /* May not match real cr4 */
/* Support for vnmi-less CPUs */
int soft_vnmi_blocked;
ktime_t entry_time;
s64 vnmi_blocked_time;
unsigned long *msr_bitmap;
struct list_head loaded_vmcss_on_cpu_link;
+ struct vmcs_host_state host_state;
};
struct shared_msr_entry {
@@ -799,12 +813,6 @@ struct vcpu_vmx {
struct vmx_msr_entry host[NR_AUTOLOAD_MSRS];
} msr_autoload;
- struct {
- u16 fs_sel, gs_sel, ldt_sel;
-#ifdef CONFIG_X86_64
- u16 ds_sel, es_sel;
-#endif
- } host_state;
struct {
int vm86_active;
ulong save_rflags;
@@ -2571,6 +2579,7 @@ static unsigned long segment_base(u16 selector)
static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct vmcs_host_state *host_state;
#ifdef CONFIG_X86_64
int cpu = raw_smp_processor_id();
#endif
@@ -2582,16 +2591,17 @@ static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
return;
vmx->loaded_cpu_state = vmx->loaded_vmcs;
+ host_state = &vmx->loaded_cpu_state->host_state;
/*
* Set host fs and gs selectors. Unfortunately, 22.2.3 does not
* allow segment selectors with cpl > 0 or ti == 1.
*/
- vmx->host_state.ldt_sel = kvm_read_ldt();
+ host_state->ldt_sel = kvm_read_ldt();
#ifdef CONFIG_X86_64
- savesegment(ds, vmx->host_state.ds_sel);
- savesegment(es, vmx->host_state.es_sel);
+ savesegment(ds, host_state->ds_sel);
+ savesegment(es, host_state->es_sel);
save_fsgs_for_kvm();
fs_sel = current->thread.fsindex;
@@ -2609,12 +2619,12 @@ static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
gs_base = segment_base(gs_sel);
#endif
- vmx->host_state.fs_sel = fs_sel;
+ host_state->fs_sel = fs_sel;
if (!(fs_sel & 7))
vmcs_write16(HOST_FS_SELECTOR, fs_sel);
else
vmcs_write16(HOST_FS_SELECTOR, 0);
- vmx->host_state.gs_sel = gs_sel;
+ host_state->gs_sel = gs_sel;
if (!(gs_sel & 7))
vmcs_write16(HOST_GS_SELECTOR, gs_sel);
else
@@ -2633,10 +2643,13 @@ static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)
{
+ struct vmcs_host_state *host_state;
+
if (!vmx->loaded_cpu_state)
return;
WARN_ON_ONCE(vmx->loaded_cpu_state != vmx->loaded_vmcs);
+ host_state = &vmx->loaded_cpu_state->host_state;
++vmx->vcpu.stat.host_state_reload;
vmx->loaded_cpu_state = NULL;
@@ -2645,20 +2658,20 @@ static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)
if (is_long_mode(&vmx->vcpu))
rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
#endif
- if (vmx->host_state.ldt_sel || (vmx->host_state.gs_sel & 7)) {
- kvm_load_ldt(vmx->host_state.ldt_sel);
+ if (host_state->ldt_sel || (host_state->gs_sel & 7)) {
+ kvm_load_ldt(host_state->ldt_sel);
#ifdef CONFIG_X86_64
- load_gs_index(vmx->host_state.gs_sel);
+ load_gs_index(host_state->gs_sel);
#else
- loadsegment(gs, vmx->host_state.gs_sel);
+ loadsegment(gs, host_state->gs_sel);
#endif
}
- if (vmx->host_state.fs_sel & 7)
- loadsegment(fs, vmx->host_state.fs_sel);
+ if (host_state->fs_sel & 7)
+ loadsegment(fs, host_state->fs_sel);
#ifdef CONFIG_X86_64
- if (unlikely(vmx->host_state.ds_sel | vmx->host_state.es_sel)) {
- loadsegment(ds, vmx->host_state.ds_sel);
- loadsegment(es, vmx->host_state.es_sel);
+ if (unlikely(host_state->ds_sel | host_state->es_sel)) {
+ loadsegment(ds, host_state->ds_sel);
+ loadsegment(es, host_state->es_sel);
}
#endif
invalidate_tss_limit();
@@ -4470,6 +4483,9 @@ static int alloc_loaded_vmcs(struct loaded_vmcs *loaded_vmcs)
evmcs->hv_enlightenments_control.msr_bitmap = 1;
}
}
+
+ memset(&loaded_vmcs->host_state, 0, sizeof(struct vmcs_host_state));
+
return 0;
out_vmcs:
@@ -5940,12 +5956,12 @@ static void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
*/
cr3 = __read_cr3();
vmcs_writel(HOST_CR3, cr3); /* 22.2.3 FIXME: shadow tables */
- vmx->loaded_vmcs->vmcs_host_cr3 = cr3;
+ vmx->loaded_vmcs->host_state.cr3 = cr3;
/* Save the most likely value for this task's CR4 in the VMCS. */
cr4 = cr4_read_shadow();
vmcs_writel(HOST_CR4, cr4); /* 22.2.3, 22.2.5 */
- vmx->loaded_vmcs->vmcs_host_cr4 = cr4;
+ vmx->loaded_vmcs->host_state.cr4 = cr4;
vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS); /* 22.2.4 */
#ifdef CONFIG_X86_64
@@ -10007,15 +10023,15 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
vmcs_writel(GUEST_RIP, vcpu->arch.regs[VCPU_REGS_RIP]);
cr3 = __get_current_cr3_fast();
- if (unlikely(cr3 != vmx->loaded_vmcs->vmcs_host_cr3)) {
+ if (unlikely(cr3 != vmx->loaded_vmcs->host_state.cr3)) {
vmcs_writel(HOST_CR3, cr3);
- vmx->loaded_vmcs->vmcs_host_cr3 = cr3;
+ vmx->loaded_vmcs->host_state.cr3 = cr3;
}
cr4 = cr4_read_shadow();
- if (unlikely(cr4 != vmx->loaded_vmcs->vmcs_host_cr4)) {
+ if (unlikely(cr4 != vmx->loaded_vmcs->host_state.cr4)) {
vmcs_writel(HOST_CR4, cr4);
- vmx->loaded_vmcs->vmcs_host_cr4 = cr4;
+ vmx->loaded_vmcs->host_state.cr4 = cr4;
}
/* When single-stepping over STI and MOV SS, we must clear the
--
2.18.0
