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KVM: TDX: vcpu_run: save/restore host state(host kernel gs)

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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@intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20250129095902.16391-7-adrian.hunter@intel.com>
Reviewed-by: Xiayao Li <xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Isaku Yamahata
2025-01-29 11:58:55 +02:00
committed by Paolo Bonzini
parent 81bf912b2c
commit 81bf40d54c
3 changed files with 66 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
arch/x86/kvm/vmx/main.c
View File

@@ -145,6 +145,26 @@ static void vt_update_cpu_dirty_logging(struct kvm_vcpu *vcpu)
vmx_update_cpu_dirty_logging(vcpu);
}
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))
@@ -265,9 +285,9 @@ 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,

40
arch/x86/kvm/vmx/tdx.c
View File

@@ -3,6 +3,7 @@
#include <linux/cpu.h>
#include <asm/cpufeature.h>
#include <linux/misc_cgroup.h>
#include <linux/mmu_context.h>
#include <asm/tdx.h>
#include "capabilities.h"
#include "mmu.h"
@@ -12,6 +13,7 @@
#include "vmx.h"
#include "mmu/spte.h"
#include "common.h"
#include "posted_intr.h"
#include <trace/events/kvm.h>
#include "trace.h"
@@ -629,6 +631,44 @@ 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_vt *vt = to_vt(vcpu);
if (vt->guest_state_loaded)
return;
if (likely(is_64bit_mm(current->mm)))
vt->msr_host_kernel_gs_base = current->thread.gsbase;
else
vt->msr_host_kernel_gs_base = read_msr(MSR_KERNEL_GS_BASE);
vt->guest_state_loaded = true;
}
static void tdx_prepare_switch_to_host(struct kvm_vcpu *vcpu)
{
struct vcpu_vt *vt = to_vt(vcpu);
if (!vt->guest_state_loaded)
return;
++vcpu->stat.host_state_reload;
wrmsrl(MSR_KERNEL_GS_BASE, vt->msr_host_kernel_gs_base);
vt->guest_state_loaded = 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);

4
arch/x86/kvm/vmx/x86_ops.h
View File

@@ -133,6 +133,8 @@ void tdx_vcpu_free(struct kvm_vcpu *vcpu);
void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
int tdx_vcpu_pre_run(struct kvm_vcpu *vcpu);
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);
@@ -164,6 +166,8 @@ 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; }