[PATCH 18/25] KVM: TDX: Do TDX specific vcpu initialization

Rick Edgecombe
2024-08-12T22:48:44Z

From: Isaku Yamahata <isaku.yamahata@intel.com>

TD guest vcpu needs TDX specific initialization before running. Repurpose
KVM_MEMORY_ENCRYPT_OP to vcpu-scope, add a new sub-command
KVM_TDX_INIT_VCPU, and implement the callback for it.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
uAPI breakout v1:
- Support FEATURES0_TOPOLOGY_ENUM
- Update for the wrapper functions for SEAMCALLs. (Sean)
- Remove WARN_ON_ONCE() in tdx_vcpu_free().
WARN_ON_ONCE(vcpu->cpu != -1), WARN_ON_ONCE(tdx->tdvpx_pa),
WARN_ON_ONCE(tdx->tdvpr_pa)
- Remove KVM_BUG_ON() in tdx_vcpu_reset().
- Remove duplicate "tdx->tdvpr_pa=" lines
- Rename tdvpx to tdcx as it is confusing, follow spec change for same
reason (Isaku)
- Updates from seamcall overhaul (Kai)
- Rename error->hw_error
- Change using tdx_info to using exported 'tdx_sysinfo' pointer in
tdx_td_vcpu_init().
- Remove code to the old (non-existing) tdx_module_setup().
- Use a new wrapper tdx_sysinfo_nr_tdcx_pages() to replace
tdx_info->nr_tdcx_pages.
- Combine the two for loops in tdx_td_vcpu_init() (Chao)
- Add more line breaks into tdx_td_vcpu_init() for readability (Tony)
- Drop Drop local tdcx_pa in tdx_td_vcpu_init() (Rick)
- Drop Drop local tdvpr_pa in tdx_td_vcpu_init() (Rick)

v18:
- Use tdh_sys_rd() instead of struct tdsysinfo_struct.
- Rename tdx_reclaim_td_page() => tdx_reclaim_control_page()
- Remove the change of tools/arch/x86/include/uapi/asm/kvm.h.
---
arch/x86/include/asm/kvm-x86-ops.h | 1 +
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/include/uapi/asm/kvm.h | 1 +
arch/x86/kvm/vmx/main.c | 9 ++
arch/x86/kvm/vmx/tdx.c | 193 ++++++++++++++++++++++++++++-
arch/x86/kvm/vmx/tdx.h | 6 +
arch/x86/kvm/vmx/tdx_arch.h | 2 +
arch/x86/kvm/vmx/x86_ops.h | 4 +
arch/x86/kvm/x86.c | 6 +
9 files changed, 221 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 12ee66bc9026..5dd7955376e3 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -126,6 +126,7 @@ KVM_X86_OP(enable_smi_window)
#endif
KVM_X86_OP_OPTIONAL(dev_get_attr)
KVM_X86_OP(mem_enc_ioctl)
+KVM_X86_OP_OPTIONAL(vcpu_mem_enc_ioctl)
KVM_X86_OP_OPTIONAL(mem_enc_register_region)
KVM_X86_OP_OPTIONAL(mem_enc_unregister_region)
KVM_X86_OP_OPTIONAL(vm_copy_enc_context_from)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 188cd684bffb..e3094c843556 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1829,6 +1829,7 @@ struct kvm_x86_ops {

int (*dev_get_attr)(u32 group, u64 attr, u64 *val);
int (*mem_enc_ioctl)(struct kvm *kvm, void __user *argp);
+ int (*vcpu_mem_enc_ioctl)(struct kvm_vcpu *vcpu, void __user *argp);
int (*mem_enc_register_region)(struct kvm *kvm, struct kvm_enc_region *argp);
int (*mem_enc_unregister_region)(struct kvm *kvm, struct kvm_enc_region *argp);
int (*vm_copy_enc_context_from)(struct kvm *kvm, unsigned int source_fd);
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 95ae2d4a4697..b4f12997052d 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -930,6 +930,7 @@ struct kvm_hyperv_eventfd {
enum kvm_tdx_cmd_id {
KVM_TDX_CAPABILITIES = 0,
KVM_TDX_INIT_VM,
+ KVM_TDX_INIT_VCPU,

KVM_TDX_CMD_NR_MAX,
};
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index d40de73d2bd3..e34cb476cc78 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -116,6 +116,14 @@ static int vt_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
return tdx_vm_ioctl(kvm, argp);
}

+static int vt_vcpu_mem_enc_ioctl(struct kvm_vcpu *vcpu, void __user *argp)
+{
+ if (!is_td_vcpu(vcpu))
+ return -EINVAL;
+
+ return tdx_vcpu_ioctl(vcpu, argp);
+}
+
#define VMX_REQUIRED_APICV_INHIBITS \
(BIT(APICV_INHIBIT_REASON_DISABLED) | \
BIT(APICV_INHIBIT_REASON_ABSENT) | \
@@ -268,6 +276,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
.get_untagged_addr = vmx_get_untagged_addr,

.mem_enc_ioctl = vt_mem_enc_ioctl,
+ .vcpu_mem_enc_ioctl = vt_vcpu_mem_enc_ioctl,
};

struct kvm_x86_init_ops vt_init_ops __initdata = {
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 18738cacbc87..ba7b436fae86 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -89,6 +89,11 @@ static __always_inline hpa_t set_hkid_to_hpa(hpa_t pa, u16 hkid)
return pa | ((hpa_t)hkid << boot_cpu_data.x86_phys_bits);
}

+static inline bool is_td_vcpu_created(struct vcpu_tdx *tdx)
+{
+ return tdx->td_vcpu_created;
+}
+
static inline bool is_td_created(struct kvm_tdx *kvm_tdx)
{
return kvm_tdx->tdr_pa;
@@ -105,6 +110,11 @@ static inline bool is_hkid_assigned(struct kvm_tdx *kvm_tdx)
return kvm_tdx->hkid > 0;
}

+static inline bool is_td_finalized(struct kvm_tdx *kvm_tdx)
+{
+ return kvm_tdx->finalized;
+}
+
static void tdx_clear_page(unsigned long page_pa)
{
const void *zero_page = (const void *) __va(page_to_phys(ZERO_PAGE(0)));
@@ -293,6 +303,15 @@ static inline u8 tdx_sysinfo_nr_tdcs_pages(void)
return tdx_sysinfo->td_ctrl.tdcs_base_size / PAGE_SIZE;
}

+static inline u8 tdx_sysinfo_nr_tdcx_pages(void)
+{
+ /*
+ * TDVPS = TDVPR(4K page) + TDCX(multiple 4K pages).
+ * -1 for TDVPR.
+ */
+ return tdx_sysinfo->td_ctrl.tdvps_base_size / PAGE_SIZE - 1;
+}
+
void tdx_vm_free(struct kvm *kvm)
{
struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
@@ -405,7 +424,29 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu)

void tdx_vcpu_free(struct kvm_vcpu *vcpu)
{
- /* This is stub for now. More logic will come. */
+ struct vcpu_tdx *tdx = to_tdx(vcpu);
+ int i;
+
+ /*
+ * This methods can be called when vcpu allocation/initialization
+ * failed. So it's possible that hkid, tdvpx and tdvpr are not assigned
+ * yet.
+ */
+ if (is_hkid_assigned(to_kvm_tdx(vcpu->kvm)))
+ return;
+
+ if (tdx->tdcx_pa) {
+ for (i = 0; i < tdx_sysinfo_nr_tdcx_pages(); i++) {
+ if (tdx->tdcx_pa[i])
+ tdx_reclaim_control_page(tdx->tdcx_pa[i]);
+ }
+ kfree(tdx->tdcx_pa);
+ tdx->tdcx_pa = NULL;
+ }
+ if (tdx->tdvpr_pa) {
+ tdx_reclaim_control_page(tdx->tdvpr_pa);
+ tdx->tdvpr_pa = 0;
+ }
}

void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
@@ -414,8 +455,13 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
/* Ignore INIT silently because TDX doesn't support INIT event. */
if (init_event)
return;
+ if (is_td_vcpu_created(to_tdx(vcpu)))
+ return;

- /* This is stub for now. More logic will come here. */
+ /*
+ * Don't update mp_state to runnable because more initialization
+ * is needed by TDX_VCPU_INIT.
+ */
}

static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
@@ -884,6 +930,149 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
return r;
}

+/* VMM can pass one 64bit auxiliary data to vcpu via RCX for guest BIOS. */
+static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
+{
+ const struct tdx_sysinfo_module_info *modinfo = &tdx_sysinfo->module_info;
+ struct vcpu_tdx *tdx = to_tdx(vcpu);
+ unsigned long va;
+ int ret, i;
+ u64 err;
+
+ if (is_td_vcpu_created(tdx))
+ return -EINVAL;
+
+ /*
+ * vcpu_free method frees allocated pages. Avoid partial setup so
+ * that the method can't handle it.
+ */
+ va = __get_free_page(GFP_KERNEL_ACCOUNT);
+ if (!va)
+ return -ENOMEM;
+ tdx->tdvpr_pa = __pa(va);
+
+ tdx->tdcx_pa = kcalloc(tdx_sysinfo_nr_tdcx_pages(), sizeof(*tdx->tdcx_pa),
+ GFP_KERNEL_ACCOUNT);
+ if (!tdx->tdcx_pa) {
+ ret = -ENOMEM;
+ goto free_tdvpr;
+ }
+
+ err = tdh_vp_create(tdx);
+ if (KVM_BUG_ON(err, vcpu->kvm)) {
+ tdx->tdvpr_pa = 0;
+ ret = -EIO;
+ pr_tdx_error(TDH_VP_CREATE, err);
+ goto free_tdvpx;
+ }
+
+ for (i = 0; i < tdx_sysinfo_nr_tdcx_pages(); i++) {
+ va = __get_free_page(GFP_KERNEL_ACCOUNT);
+ if (!va) {
+ ret = -ENOMEM;
+ goto free_tdvpx;
+ }
+ tdx->tdcx_pa[i] = __pa(va);
+
+ err = tdh_vp_addcx(tdx, tdx->tdcx_pa[i]);
+ if (KVM_BUG_ON(err, vcpu->kvm)) {
+ pr_tdx_error(TDH_VP_ADDCX, err);
+ /* vcpu_free method frees TDCX and TDR donated to TDX */
+ return -EIO;
+ }
+ }
+
+ if (modinfo->tdx_features0 & MD_FIELD_ID_FEATURES0_TOPOLOGY_ENUM)
+ err = tdh_vp_init_apicid(tdx, vcpu_rcx, vcpu->vcpu_id);
+ else
+ err = tdh_vp_init(tdx, vcpu_rcx);
+
+ if (KVM_BUG_ON(err, vcpu->kvm)) {
+ pr_tdx_error(TDH_VP_INIT, err);
+ return -EIO;
+ }
+
+ vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
+ tdx->td_vcpu_created = true;
+
+ return 0;
+
+free_tdvpx:
+ for (i = 0; i < tdx_sysinfo_nr_tdcx_pages(); i++) {
+ if (tdx->tdcx_pa[i])
+ free_page((unsigned long)__va(tdx->tdcx_pa[i]));
+ tdx->tdcx_pa[i] = 0;
+ }
+ kfree(tdx->tdcx_pa);
+ tdx->tdcx_pa = NULL;
+
+free_tdvpr:
+ if (tdx->tdvpr_pa)
+ free_page((unsigned long)__va(tdx->tdvpr_pa));
+ tdx->tdvpr_pa = 0;
+
+ return ret;
+}
+
+static int tdx_vcpu_init(struct kvm_vcpu *vcpu, struct kvm_tdx_cmd *cmd)
+{
+ struct msr_data apic_base_msr;
+ struct vcpu_tdx *tdx = to_tdx(vcpu);
+ int ret;
+
+ if (cmd->flags)
+ return -EINVAL;
+ if (tdx->initialized)
+ return -EINVAL;
+
+ /*
+ * As TDX requires X2APIC, set local apic mode to X2APIC. User space
+ * VMM, e.g. qemu, is required to set CPUID[0x1].ecx.X2APIC=1 by
+ * KVM_SET_CPUID2. Otherwise kvm_set_apic_base() will fail.
+ */
+ apic_base_msr = (struct msr_data) {
+ .host_initiated = true,
+ .data = APIC_DEFAULT_PHYS_BASE | LAPIC_MODE_X2APIC |
+ (kvm_vcpu_is_reset_bsp(vcpu) ? MSR_IA32_APICBASE_BSP : 0),
+ };
+ if (kvm_set_apic_base(vcpu, &apic_base_msr))
+ return -EINVAL;
+
+ ret = tdx_td_vcpu_init(vcpu, (u64)cmd->data);
+ if (ret)
+ return ret;
+
+ tdx->initialized = true;
+ return 0;
+}
+
+int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp)
+{
+ struct kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm);
+ struct kvm_tdx_cmd cmd;
+ int ret;
+
+ if (!is_hkid_assigned(kvm_tdx) || is_td_finalized(kvm_tdx))
+ return -EINVAL;
+
+ if (copy_from_user(&cmd, argp, sizeof(cmd)))
+ return -EFAULT;
+
+ if (cmd.hw_error)
+ return -EINVAL;
+
+ switch (cmd.id) {
+ case KVM_TDX_INIT_VCPU:
+ ret = tdx_vcpu_init(vcpu, &cmd);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ return ret;
+}
+
#define KVM_SUPPORTED_TD_ATTRS (TDX_TD_ATTR_SEPT_VE_DISABLE)

static int __init setup_kvm_tdx_caps(void)
diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
index ca948f26b755..8349b542836e 100644
--- a/arch/x86/kvm/vmx/tdx.h
+++ b/arch/x86/kvm/vmx/tdx.h
@@ -22,6 +22,8 @@ struct kvm_tdx {
u64 xfam;
int hkid;

+ bool finalized;
+
u64 tsc_offset;
};

@@ -29,6 +31,10 @@ struct vcpu_tdx {
struct kvm_vcpu vcpu;

unsigned long tdvpr_pa;
+ unsigned long *tdcx_pa;
+ bool td_vcpu_created;
+
+ bool initialized;

/*
* Dummy to make pmu_intel not corrupt memory.
diff --git a/arch/x86/kvm/vmx/tdx_arch.h b/arch/x86/kvm/vmx/tdx_arch.h
index 413619dd92ef..d2d7f9cab740 100644
--- a/arch/x86/kvm/vmx/tdx_arch.h
+++ b/arch/x86/kvm/vmx/tdx_arch.h
@@ -155,4 +155,6 @@ struct td_params {
#define TDX_MIN_TSC_FREQUENCY_KHZ (100 * 1000)
#define TDX_MAX_TSC_FREQUENCY_KHZ (10 * 1000 * 1000)

+#define MD_FIELD_ID_FEATURES0_TOPOLOGY_ENUM BIT_ULL(20)
+
#endif /* __KVM_X86_TDX_ARCH_H */
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index e1d3276b0f60..55fd17fbfd19 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -129,6 +129,8 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
int tdx_vcpu_create(struct kvm_vcpu *vcpu);
void tdx_vcpu_free(struct kvm_vcpu *vcpu);
void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event);
+
+int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);
#else
static inline int tdx_vm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
{
@@ -143,6 +145,8 @@ static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOP
static inline int tdx_vcpu_create(struct kvm_vcpu *vcpu) { return -EOPNOTSUPP; }
static inline void tdx_vcpu_free(struct kvm_vcpu *vcpu) {}
static inline void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) {}
+
+static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }
#endif

#endif /* __KVM_X86_VMX_X86_OPS_H */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9cee326f5e7a..3d43fa84c2b4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6314,6 +6314,12 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
case KVM_SET_DEVICE_ATTR:
r = kvm_vcpu_ioctl_device_attr(vcpu, ioctl, argp);
break;
+ case KVM_MEMORY_ENCRYPT_OP:
+ r = -ENOTTY;
+ if (!kvm_x86_ops.vcpu_mem_enc_ioctl)
+ goto out;
+ r = kvm_x86_ops.vcpu_mem_enc_ioctl(vcpu, argp);
+ break;
default:
r = -EINVAL;
}
--
2.34.1