[RFC PATCH v1 20/28] KVM: SVM: prepare for SEV guest management API support

[Brijesh Singh]

The patch adds initial support required for Secure Encrypted
Virtualization (SEV) guest management API's.

ASID management:
 - Reserve asid range for SEV guest, SEV asid range is obtained
   through CPUID Fn8000_001f[ECX]. A non-SEV guest can use any
   asid outside the SEV asid range.
 - SEV guest must have asid value within asid range obtained
   through CPUID.
 - SEV guest must have the same asid for all vcpu's. A TLB flush
   is required if different vcpu for the same ASID is to be run
   on the same host CPU.

- save SEV private structure in kvm_arch.

- If SEV is available then initialize PSP firmware during hardware probe

Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
 arch/x86/include/asm/kvm_host.h |    9 ++
 arch/x86/kvm/svm.c              |  213 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 221 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b1dd673..9b885fc 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -715,6 +715,12 @@ struct kvm_hv {
 	u64 hv_crash_ctl;
 };
 
+struct kvm_sev_info {
+	unsigned int asid;	/* asid for this guest */
+	unsigned int handle;	/* firmware handle */
+	unsigned int ref_count; /* number of active vcpus */
+};
+
 struct kvm_arch {
 	unsigned int n_used_mmu_pages;
 	unsigned int n_requested_mmu_pages;
@@ -799,6 +805,9 @@ struct kvm_arch {
 
 	bool x2apic_format;
 	bool x2apic_broadcast_quirk_disabled;
+
+	/* struct for SEV guest */
+	struct kvm_sev_info sev_info;
 };
 
 struct kvm_vm_stat {
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f010b23..dcee635 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -34,6 +34,7 @@
 #include <linux/sched.h>
 #include <linux/trace_events.h>
 #include <linux/slab.h>
+#include <linux/ccp-psp.h>
 
 #include <asm/apic.h>
 #include <asm/perf_event.h>
@@ -186,6 +187,9 @@ struct vcpu_svm {
 	struct page *avic_backing_page;
 	u64 *avic_physical_id_cache;
 	bool avic_is_running;
+
+	/* which host cpu was used for running this vcpu */
+	bool last_cpuid;
 };
 
 #define AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK	(0xFF)
@@ -243,6 +247,25 @@ static int avic;
 module_param(avic, int, S_IRUGO);
 #endif
 
+/* Secure Encrypted Virtualization */
+static bool sev_enabled;
+static unsigned long max_sev_asid;
+static unsigned long *sev_asid_bitmap;
+
+#define kvm_sev_guest()		(kvm->arch.sev_info.handle)
+#define kvm_sev_handle()	(kvm->arch.sev_info.handle)
+#define kvm_sev_ref()		(kvm->arch.sev_info.ref_count++)
+#define kvm_sev_unref()		(kvm->arch.sev_info.ref_count--)
+#define svm_sev_handle()	(svm->vcpu.kvm->arch.sev_info.handle)
+#define svm_sev_asid()		(svm->vcpu.kvm->arch.sev_info.asid)
+#define svm_sev_ref()		(svm->vcpu.kvm->arch.sev_info.ref_count++)
+#define svm_sev_unref()		(svm->vcpu.kvm->arch.sev_info.ref_count--)
+#define svm_sev_guest()		(svm->vcpu.kvm->arch.sev_info.handle)
+#define svm_sev_ref_count()	(svm->vcpu.kvm->arch.sev_info.ref_count)
+
+static int sev_asid_new(void);
+static void sev_asid_free(int asid);
+
 static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
 static void svm_flush_tlb(struct kvm_vcpu *vcpu);
 static void svm_complete_interrupts(struct vcpu_svm *svm);
@@ -474,6 +497,8 @@ struct svm_cpu_data {
 	struct kvm_ldttss_desc *tss_desc;
 
 	struct page *save_area;
+
+	void **sev_vmcb;  /* index = sev_asid, value = vmcb pointer */
 };
 
 static DEFINE_PER_CPU(struct svm_cpu_data *, svm_data);
@@ -727,7 +752,10 @@ static int svm_hardware_enable(void)
 	sd->asid_generation = 1;
 	sd->max_asid = cpuid_ebx(SVM_CPUID_FUNC) - 1;
 	sd->next_asid = sd->max_asid + 1;
-	sd->min_asid = 1;
+	sd->min_asid = max_sev_asid + 1;
+
+	if (sev_enabled)
+		memset(sd->sev_vmcb, 0, (max_sev_asid + 1) * sizeof(void *));
 
 	native_store_gdt(&gdt_descr);
 	gdt = (struct desc_struct *)gdt_descr.address;
@@ -788,6 +816,7 @@ static void svm_cpu_uninit(int cpu)
 
 	per_cpu(svm_data, raw_smp_processor_id()) = NULL;
 	__free_page(sd->save_area);
+	kfree(sd->sev_vmcb);
 	kfree(sd);
 }
 
@@ -805,6 +834,14 @@ static int svm_cpu_init(int cpu)
 	if (!sd->save_area)
 		goto err_1;
 
+	if (sev_enabled) {
+		sd->sev_vmcb = kmalloc((max_sev_asid + 1) * sizeof(void *),
+					GFP_KERNEL);
+		r = -ENOMEM;
+		if (!sd->sev_vmcb)
+			goto err_1;
+	}
+
 	per_cpu(svm_data, cpu) = sd;
 
 	return 0;
@@ -931,6 +968,74 @@ static void svm_disable_lbrv(struct vcpu_svm *svm)
 	set_msr_interception(msrpm, MSR_IA32_LASTINTTOIP, 0, 0);
 }
 
+static __init void sev_hardware_setup(void)
+{
+	int ret, psp_ret;
+	struct psp_data_init *init;
+	struct psp_data_status *status;
+
+	/*
+	 * Check SEV Feature Support: Fn8001_001F[EAX]
+	 * 	Bit 1: Secure Memory Virtualization supported
+	 */
+	if (!(cpuid_eax(0x8000001F) & 0x2))
+		return;
+
+	/*
+	 * Get maximum number of encrypted guest supported: Fn8001_001F[ECX]
+	 * 	Bit 31:0: Number of supported guest
+	 */
+	max_sev_asid = cpuid_ecx(0x8000001F);
+	if (!max_sev_asid)
+		return;
+
+	init = kzalloc(sizeof(*init), GFP_KERNEL);
+	if (!init)
+		return;
+
+	status = kzalloc(sizeof(*status), GFP_KERNEL);
+	if (!status)
+		goto err_1;
+
+	/* Initialize PSP firmware */
+	init->hdr.buffer_len = sizeof(*init);
+	init->flags = 0;
+	ret = psp_platform_init(init, &psp_ret);
+	if (ret) {
+		printk(KERN_ERR "SEV: PSP_INIT ret=%d (%#x)\n", ret, psp_ret);
+		goto err_2;
+	}
+
+	/* Initialize SEV ASID bitmap */
+	sev_asid_bitmap = kmalloc(max(sizeof(unsigned long),
+				      max_sev_asid/8 + 1), GFP_KERNEL);
+	if (IS_ERR(sev_asid_bitmap)) {
+		psp_platform_shutdown(&psp_ret);
+		goto err_2;
+	}
+	bitmap_zero(sev_asid_bitmap, max_sev_asid);
+	set_bit(0, sev_asid_bitmap);  /* mark ASID 0 as used */
+
+	sev_enabled = 1;
+	printk(KERN_INFO "kvm: SEV enabled\n");
+
+	/* Query the platform status and print API version */
+	status->hdr.buffer_len = sizeof(*status);
+	ret = psp_platform_status(status, &psp_ret);
+	if (ret) {
+		printk(KERN_ERR "SEV: PLATFORM_STATUS ret=%#x\n", psp_ret);
+		goto err_2;
+	}
+
+	printk(KERN_INFO "SEV API: %d.%d\n",
+			status->api_major, status->api_minor);
+err_2:
+	kfree(status);
+err_1:
+	kfree(init);
+	return;
+}
+
 static __init int svm_hardware_setup(void)
 {
 	int cpu;
@@ -966,6 +1071,8 @@ static __init int svm_hardware_setup(void)
 		kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE);
 	}
 
+	sev_hardware_setup();
+
 	for_each_possible_cpu(cpu) {
 		r = svm_cpu_init(cpu);
 		if (r)
@@ -1003,10 +1110,25 @@ err:
 	return r;
 }
 
+static __exit void sev_hardware_unsetup(void)
+{
+	int ret, psp_ret;
+
+	ret = psp_platform_shutdown(&psp_ret);
+	if (ret)
+		printk(KERN_ERR "failed to shutdown PSP rc=%d (%#0x10x)\n",
+		ret, psp_ret);
+
+	kfree(sev_asid_bitmap);
+}
+
 static __exit void svm_hardware_unsetup(void)
 {
 	int cpu;
 
+	if (sev_enabled)
+		sev_hardware_unsetup();
+
 	for_each_possible_cpu(cpu)
 		svm_cpu_uninit(cpu);
 
@@ -1088,6 +1210,11 @@ static void avic_init_vmcb(struct vcpu_svm *svm)
 	svm->vcpu.arch.apicv_active = true;
 }
 
+static void sev_init_vmcb(struct vcpu_svm *svm)
+{
+	svm->vmcb->control.nested_ctl |= SVM_NESTED_CTL_SEV_ENABLE;
+}
+
 static void init_vmcb(struct vcpu_svm *svm)
 {
 	struct vmcb_control_area *control = &svm->vmcb->control;
@@ -1202,6 +1329,10 @@ static void init_vmcb(struct vcpu_svm *svm)
 	if (avic)
 		avic_init_vmcb(svm);
 
+	if (svm_sev_guest())
+		sev_init_vmcb(svm);
+
+
 	mark_all_dirty(svm->vmcb);
 
 	enable_gif(svm);
@@ -1413,6 +1544,14 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 		avic_update_vapic_bar(svm, APIC_DEFAULT_PHYS_BASE);
 }
 
+static void sev_init_vcpu(struct vcpu_svm *svm)
+{
+	if (!svm_sev_guest())
+		return;
+
+	svm_sev_ref();
+}
+
 static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
 {
 	struct vcpu_svm *svm;
@@ -1475,6 +1614,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
 	init_vmcb(svm);
 
 	svm_init_osvw(&svm->vcpu);
+	sev_init_vcpu(svm);
 
 	return &svm->vcpu;
 
@@ -1494,6 +1634,23 @@ out:
 	return ERR_PTR(err);
 }
 
+static void sev_uninit_vcpu(struct vcpu_svm *svm)
+{
+	int cpu;
+	int asid = svm_sev_asid();
+	struct svm_cpu_data *sd;
+
+	if (!svm_sev_guest())
+		return;
+
+	svm_sev_unref();
+
+	for_each_possible_cpu(cpu) {
+		sd = per_cpu(svm_data, cpu);
+		sd->sev_vmcb[asid] = NULL;
+	}
+}
+
 static void svm_free_vcpu(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
@@ -1502,6 +1659,7 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
 	__free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);
 	__free_page(virt_to_page(svm->nested.hsave));
 	__free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER);
+	sev_uninit_vcpu(svm);
 	kvm_vcpu_uninit(vcpu);
 	kmem_cache_free(kvm_vcpu_cache, svm);
 }
@@ -1945,6 +2103,11 @@ static int pf_interception(struct vcpu_svm *svm)
 	default:
 		error_code = svm->vmcb->control.exit_info_1;
 
+		/* In SEV mode, the guest physical address will have C-bit
+		 * set. C-bit must be cleared before handling the fault.
+		 */
+		if (svm_sev_guest())
+			fault_address &= ~sme_me_mask;
 		trace_kvm_page_fault(fault_address, error_code);
 		if (!npt_enabled && kvm_event_needs_reinjection(&svm->vcpu))
 			kvm_mmu_unprotect_page_virt(&svm->vcpu, fault_address);
@@ -4131,12 +4294,40 @@ static void reload_tss(struct kvm_vcpu *vcpu)
 	load_TR_desc();
 }
 
+static void pre_sev_run(struct vcpu_svm *svm)
+{
+	int asid = svm_sev_asid();
+	int cpu = raw_smp_processor_id();
+	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
+
+	/* Assign the asid allocated for this SEV guest */
+	svm->vmcb->control.asid = svm_sev_asid();
+
+	/* Flush guest TLB:
+	 * - when different VMCB for the same ASID is to be run on the
+	 *   same host CPU
+	 *   or 
+	 * - this VMCB was executed on different host cpu in previous VMRUNs.
+	 */
+	if (sd->sev_vmcb[asid] != (void *)svm->vmcb ||
+		svm->last_cpuid != cpu)
+		svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ALL_ASID;
+
+	svm->last_cpuid = cpu;
+	sd->sev_vmcb[asid] = (void *)svm->vmcb;
+
+	mark_dirty(svm->vmcb, VMCB_ASID);
+}
+
 static void pre_svm_run(struct vcpu_svm *svm)
 {
 	int cpu = raw_smp_processor_id();
 
 	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
 
+	if (svm_sev_guest())
+		return pre_sev_run(svm);
+
 	/* FIXME: handle wraparound of asid_generation */
 	if (svm->asid_generation != sd->asid_generation)
 		new_asid(svm, sd);
@@ -4985,6 +5176,26 @@ static inline void avic_post_state_restore(struct kvm_vcpu *vcpu)
 	avic_handle_ldr_update(vcpu);
 }
 
+static int sev_asid_new(void)
+{
+	int pos;
+
+	if (!sev_enabled)
+		return -ENOTTY;
+
+	pos = find_first_zero_bit(sev_asid_bitmap, max_sev_asid);
+	if (pos >= max_sev_asid)
+		return -EBUSY;
+
+	set_bit(pos, sev_asid_bitmap);
+	return pos;
+}
+
+static void sev_asid_free(int asid)
+{
+	clear_bit(asid, sev_asid_bitmap);
+}
+
 static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 	.cpu_has_kvm_support = has_svm,
 	.disabled_by_bios = is_disabled,