From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
On entering/exiting TDX vcpu, preserved or clobbered CPU state is different
from the VMX case. Add TDX hooks to save/restore host/guest CPU state.
Save/restore kernel GS base MSR.
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
TD vcpu enter/exit v1:
- Clarify comment (Binbin)
- Use lower case preserved and add the for VMX in log (Tony)
- Fix bisectability issue with includes (Kai)
---
arch/x86/kvm/vmx/main.c | 24 ++++++++++++++++++--
arch/x86/kvm/vmx/tdx.c | 46 ++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/vmx/tdx.h | 4 ++++
arch/x86/kvm/vmx/x86_ops.h | 4 ++++
4 files changed, 76 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 44ec6005a448..3a8ffc199be2 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -129,6 +129,26 @@ static void vt_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
vmx_vcpu_load(vcpu, cpu);
}
+static void vt_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
+{
+ if (is_td_vcpu(vcpu)) {
+ tdx_prepare_switch_to_guest(vcpu);
+ return;
+ }
+
+ vmx_prepare_switch_to_guest(vcpu);
+}
+
+static void vt_vcpu_put(struct kvm_vcpu *vcpu)
+{
+ if (is_td_vcpu(vcpu)) {
+ tdx_vcpu_put(vcpu);
+ return;
+ }
+
+ vmx_vcpu_put(vcpu);
+}
+
static int vt_vcpu_pre_run(struct kvm_vcpu *vcpu)
{
if (is_td_vcpu(vcpu))
@@ -250,9 +270,9 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
.vcpu_free = vt_vcpu_free,
.vcpu_reset = vt_vcpu_reset,
- .prepare_switch_to_guest = vmx_prepare_switch_to_guest,
+ .prepare_switch_to_guest = vt_prepare_switch_to_guest,
.vcpu_load = vt_vcpu_load,
- .vcpu_put = vmx_vcpu_put,
+ .vcpu_put = vt_vcpu_put,
.update_exception_bitmap = vmx_update_exception_bitmap,
.get_feature_msr = vmx_get_feature_msr,
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 5fa5b65b9588..6e4ea2d420bc 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/cleanup.h>
#include <linux/cpu.h>
+#include <linux/mmu_context.h>
#include <asm/tdx.h>
#include "capabilities.h"
#include "mmu.h"
@@ -9,6 +10,7 @@
#include "vmx.h"
#include "mmu/spte.h"
#include "common.h"
+#include "posted_intr.h"
#include <trace/events/kvm.h>
#include "trace.h"
@@ -605,6 +607,9 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu)
if ((kvm_tdx->xfam & XFEATURE_MASK_XTILE) == XFEATURE_MASK_XTILE)
vcpu->arch.xfd_no_write_intercept = true;
+ tdx->host_state_need_save = true;
+ tdx->host_state_need_restore = false;
+
tdx->state = VCPU_TD_STATE_UNINITIALIZED;
return 0;
@@ -631,6 +636,45 @@ void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
local_irq_enable();
}
+/*
+ * Compared to vmx_prepare_switch_to_guest(), there is not much to do
+ * as SEAMCALL/SEAMRET calls take care of most of save and restore.
+ */
+void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_tdx *tdx = to_tdx(vcpu);
+
+ if (!tdx->host_state_need_save)
+ return;
+
+ if (likely(is_64bit_mm(current->mm)))
+ tdx->msr_host_kernel_gs_base = current->thread.gsbase;
+ else
+ tdx->msr_host_kernel_gs_base = read_msr(MSR_KERNEL_GS_BASE);
+
+ tdx->host_state_need_save = false;
+}
+
+static void tdx_prepare_switch_to_host(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_tdx *tdx = to_tdx(vcpu);
+
+ tdx->host_state_need_save = true;
+ if (!tdx->host_state_need_restore)
+ return;
+
+ ++vcpu->stat.host_state_reload;
+
+ wrmsrl(MSR_KERNEL_GS_BASE, tdx->msr_host_kernel_gs_base);
+ tdx->host_state_need_restore = false;
+}
+
+void tdx_vcpu_put(struct kvm_vcpu *vcpu)
+{
+ vmx_vcpu_pi_put(vcpu);
+ tdx_prepare_switch_to_host(vcpu);
+}
+
void tdx_vcpu_free(struct kvm_vcpu *vcpu)
{
struct kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm);
@@ -732,6 +776,8 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
tdx_vcpu_enter_exit(vcpu);
+ tdx->host_state_need_restore = true;
+
vcpu->arch.regs_avail &= ~VMX_REGS_LAZY_LOAD_SET;
trace_kvm_exit(vcpu, KVM_ISA_VMX);
diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
index ebee1049b08b..48cf0a1abfcc 100644
--- a/arch/x86/kvm/vmx/tdx.h
+++ b/arch/x86/kvm/vmx/tdx.h
@@ -54,6 +54,10 @@ struct vcpu_tdx {
u64 vp_enter_ret;
enum vcpu_tdx_state state;
+
+ bool host_state_need_save;
+ bool host_state_need_restore;
+ u64 msr_host_kernel_gs_base;
};
void tdh_vp_rd_failed(struct vcpu_tdx *tdx, char *uclass, u32 field, u64 err);
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index 3d292a677b92..5bd45a720007 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -130,6 +130,8 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu);
void tdx_vcpu_free(struct kvm_vcpu *vcpu);
void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit);
+void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu);
+void tdx_vcpu_put(struct kvm_vcpu *vcpu);
int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);
@@ -161,6 +163,8 @@ static inline fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediat
{
return EXIT_FASTPATH_NONE;
}
+static inline void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) {}
+static inline void tdx_vcpu_put(struct kvm_vcpu *vcpu) {}
static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }
--
2.43.0
