Subject: [RFC PATCH v4 6/6] kvmppc: Support reset of secure guest

From: Bharata B Rao <[email-masked]>
Date: Tue, 28 May 2019 12:19:33 +0530

Add support for reset of secure guest via a new ioctl KVM_PPC_SVM_OFF.
This ioctl will be issued by QEMU during reset and in this ioctl,
we ask UV to terminate the guest via UV_SVM_TERMINATE ucall,
reinitialize guest's partitioned scoped page tables and release all
HMM pages of the secure guest.

After these steps, guest is ready to issue UV_ESM call once again
to switch to secure mode.

Signed-off-by: Bharata B Rao <[email-masked]>
Signed-off-by: Sukadev Bhattiprolu <[email-masked]>
	[Implementation of uv_svm_terminate() and its call from
	guest shutdown path]
---
 arch/powerpc/include/asm/kvm_host.h       |  6 ++
 arch/powerpc/include/asm/kvm_ppc.h        |  4 ++
 arch/powerpc/include/asm/ultravisor-api.h |  1 +
 arch/powerpc/include/asm/ultravisor.h     |  7 ++
 arch/powerpc/kvm/book3s_hv.c              | 23 +++++++
 arch/powerpc/kvm/book3s_hv_hmm.c          | 83 +++++++++++++++++++++++
 arch/powerpc/kvm/powerpc.c                | 12 ++++
 include/uapi/linux/kvm.h                  |  1 +
 tools/include/uapi/linux/kvm.h            |  1 +
 9 files changed, 138 insertions(+)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 63d56f7a357e..c220bcfe7726 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -868,6 +868,7 @@ extern void kvmppc_hmm_free(void);
 extern void kvmppc_hmm_release_pfns(struct kvm_memory_slot *free);
 extern bool kvmppc_is_guest_secure(struct kvm *kvm);
 extern int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gpa);
+extern int kvmppc_hmm_svm_off(struct kvm *kvm);
 #else
 static inline int kvmppc_hmm_init(void)
 {
@@ -887,6 +888,11 @@ static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gpa)
 {
 	return -EFAULT;
 }
+
+static inline int kvmppc_hmm_svm_off(struct kvm *kvm)
+{
+	return 0;
+}
 #endif /* CONFIG_PPC_UV */
 
 #endif /* __POWERPC_KVM_HOST_H__ */
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index bc892380e6cd..aee4b81e9558 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -188,6 +188,7 @@ extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm,
 extern int kvmppc_switch_mmu_to_hpt(struct kvm *kvm);
 extern int kvmppc_switch_mmu_to_radix(struct kvm *kvm);
 extern void kvmppc_setup_partition_table(struct kvm *kvm);
+extern int kvmppc_reinit_partition_table(struct kvm *kvm);
 
 extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
 				struct kvm_create_spapr_tce_64 *args);
@@ -332,6 +333,7 @@ struct kvmppc_ops {
 			       int size);
 	int (*store_to_eaddr)(struct kvm_vcpu *vcpu, ulong *eaddr, void *ptr,
 			      int size);
+	int (*svm_off)(struct kvm *kvm);
 };
 
 extern struct kvmppc_ops *kvmppc_hv_ops;
@@ -961,5 +963,7 @@ static inline ulong kvmppc_get_ea_indexed(struct kvm_vcpu *vcpu, int ra, int rb)
 }
 
 extern void xics_wake_cpu(int cpu);
+extern void kvmppc_hmm_free_memslot_pfns(struct kvm *kvm,
+					 struct kvm_memslots *slots);
 
 #endif /* __POWERPC_KVM_PPC_H__ */
diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h
index eaca65ea2070..6d59c64f30ce 100644
--- a/arch/powerpc/include/asm/ultravisor-api.h
+++ b/arch/powerpc/include/asm/ultravisor-api.h
@@ -25,5 +25,6 @@
 #define UV_PAGE_IN			0xF128
 #define UV_PAGE_OUT			0xF12C
 #define UV_PAGE_INVAL			0xF138
+#define UV_SVM_TERMINATE		0xF13C
 
 #endif /* _ASM_POWERPC_ULTRAVISOR_API_H */
diff --git a/arch/powerpc/include/asm/ultravisor.h b/arch/powerpc/include/asm/ultravisor.h
index 28dbc0f0eddb..1c60b7328f09 100644
--- a/arch/powerpc/include/asm/ultravisor.h
+++ b/arch/powerpc/include/asm/ultravisor.h
@@ -84,6 +84,13 @@ static inline int uv_page_inval(u64 lpid, u64 gpa, u64 page_shift)
 
 	return ucall(UV_PAGE_INVAL, retbuf, lpid, gpa, page_shift);
 }
+
+static inline int uv_svm_terminate(u64 lpid)
+{
+	unsigned long retbuf[UCALL_BUFSIZE];
+
+	return ucall(UV_SVM_TERMINATE, retbuf, lpid);
+}
 #endif /* !__ASSEMBLY__ */
 
 #endif	/* _ASM_POWERPC_ULTRAVISOR_H */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 5ef35e230453..4a423c92fb18 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4571,6 +4571,22 @@ void kvmppc_setup_partition_table(struct kvm *kvm)
 	kvmhv_set_ptbl_entry(kvm->arch.lpid, dw0, dw1);
 }
 
+/*
+ * Called from KVM_PPC_SVM_OFF ioctl at guest reset time when secure
+ * guest is converted back to normal guest.
+ */
+int kvmppc_reinit_partition_table(struct kvm *kvm)
+{
+	int ret;
+
+	ret = kvmppc_init_vm_radix(kvm);
+	if (ret)
+		return ret;
+
+	kvmppc_setup_partition_table(kvm);
+	return 0;
+}
+
 /*
  * Set up HPT (hashed page table) and RMA (real-mode area).
  * Must be called with kvm->lock held.
@@ -4950,6 +4966,7 @@ static void kvmppc_core_destroy_vm_hv(struct kvm *kvm)
 		if (nesting_enabled(kvm))
 			kvmhv_release_all_nested(kvm);
 		kvm->arch.process_table = 0;
+		uv_svm_terminate(kvm->arch.lpid);
 		kvmhv_set_ptbl_entry(kvm->arch.lpid, 0, 0);
 	}
 	kvmppc_free_lpid(kvm->arch.lpid);
@@ -5391,6 +5408,11 @@ static int kvmhv_store_to_eaddr(struct kvm_vcpu *vcpu, ulong *eaddr, void *ptr,
 	return rc;
 }
 
+static int kvmhv_svm_off(struct kvm *kvm)
+{
+	return kvmppc_hmm_svm_off(kvm);
+}
+
 static struct kvmppc_ops kvm_ops_hv = {
 	.get_sregs = kvm_arch_vcpu_ioctl_get_sregs_hv,
 	.set_sregs = kvm_arch_vcpu_ioctl_set_sregs_hv,
@@ -5433,6 +5455,7 @@ static struct kvmppc_ops kvm_ops_hv = {
 	.enable_nested = kvmhv_enable_nested,
 	.load_from_eaddr = kvmhv_load_from_eaddr,
 	.store_to_eaddr = kvmhv_store_to_eaddr,
+	.svm_off = kvmhv_svm_off,
 };
 
 static int kvm_init_subcore_bitmap(void)
diff --git a/arch/powerpc/kvm/book3s_hv_hmm.c b/arch/powerpc/kvm/book3s_hv_hmm.c
index a0d47fc140b6..c9ce8b003ef5 100644
--- a/arch/powerpc/kvm/book3s_hv_hmm.c
+++ b/arch/powerpc/kvm/book3s_hv_hmm.c
@@ -31,6 +31,8 @@
 #include <linux/kvm_host.h>
 #include <linux/sched/mm.h>
 #include <asm/ultravisor.h>
+#include <asm/kvm_ppc.h>
+#include <asm/kvm_book3s.h>
 
 struct kvmppc_hmm_device {
 	struct hmm_device *device;
@@ -60,6 +62,30 @@ bool kvmppc_is_guest_secure(struct kvm *kvm)
 	return !!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE);
 }
 
+int kvmppc_hmm_svm_off(struct kvm *kvm)
+{
+	int ret = 0;
+	int i;
+
+	if (kvmppc_is_guest_secure(kvm)) {
+		ret = uv_svm_terminate(kvm->arch.lpid);
+		if (ret != U_SUCCESS) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = kvmppc_reinit_partition_table(kvm);
+		if (ret)
+			goto out;
+		kvm->arch.secure_guest = 0;
+		for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
+			kvmppc_hmm_free_memslot_pfns(kvm,
+			__kvm_memslots(kvm, i));
+	}
+out:
+	return ret;
+}
+
 unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
 {
 	struct kvm_memslots *slots;
@@ -91,6 +117,11 @@ unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)
 		return H_UNSUPPORTED;
 
 	kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE;
+	if (kvm_is_radix(kvm)) {
+		pr_info("Guest went secure, freeing HV side radix pgtables\n");
+		kvmppc_free_radix(kvm);
+	}
+
 	return H_SUCCESS;
 }
 
@@ -113,6 +144,58 @@ void kvmppc_hmm_release_pfns(struct kvm_memory_slot *free)
 	}
 }
 
+/*
+ * Drop HMM pages that we maintain for the secure guest
+ *
+ * We mark the pages to be skipped from UV_PAGE_OUT when there is HMM
+ * fault on these pages. Next we get these pages, force HMM fault,
+ * do fault migration to replace the HMM PTEs from QEMU page tables
+ * with normal PTEs from newly allocated pages.
+ */
+static void kvmppc_hmm_drop_pages(struct kvm_memory_slot *free, struct kvm *kvm)
+{
+	int i;
+	struct kvmppc_hmm_page_pvt *pvt;
+	unsigned long pfn;
+
+	for (i = 0; i < free->npages; i++) {
+		unsigned long *rmap = &free->arch.rmap[i];
+		struct page *hmm_page;
+
+		if (kvmppc_is_hmm_pfn(*rmap)) {
+			hmm_page = pfn_to_page(*rmap & ~KVMPPC_PFN_HMM);
+			pvt = (struct kvmppc_hmm_page_pvt *)
+				hmm_devmem_page_get_drvdata(hmm_page);
+			pvt->skip_page_out = true;
+
+			pfn = gfn_to_pfn(kvm, pvt->gpa >> PAGE_SHIFT);
+			if (is_error_noslot_pfn(pfn))
+				continue;
+			kvm_release_pfn_clean(pfn);
+		}
+	}
+}
+
+/*
+ * Called from KVM_PPC_SVM_OFF ioctl when secure guest is reset
+ *
+ * UV has already cleaned up the guest, we release any HMM pages that
+ * we maintain
+ */
+void kvmppc_hmm_free_memslot_pfns(struct kvm *kvm, struct kvm_memslots *slots)
+{
+	struct kvm_memory_slot *memslot;
+	int srcu_idx;
+
+	if (!slots)
+		return;
+
+	srcu_idx = srcu_read_lock(&kvm->srcu);
+	kvm_for_each_memslot(memslot, slots)
+		kvmppc_hmm_drop_pages(memslot, kvm);
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+}
+
 /*
  * Get a free HMM PFN from the pool
  *
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 3393b166817a..0c5fae004adf 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -42,6 +42,8 @@
 #include <asm/hvcall.h>
 #include <asm/plpar_wrappers.h>
 #endif
+#include <asm/ultravisor.h>
+#include <asm/kvm_host.h>
 
 #include "timing.h"
 #include "irq.h"
@@ -2423,6 +2425,16 @@ long kvm_arch_vm_ioctl(struct file *filp,
 			r = -EFAULT;
 		break;
 	}
+	case KVM_PPC_SVM_OFF: {
+		struct kvm *kvm = filp->private_data;
+
+		r = 0;
+		if (!kvm->arch.kvm_ops->svm_off)
+			goto out;
+
+		r = kvm->arch.kvm_ops->svm_off(kvm);
+		break;
+	}
 	default: {
 		struct kvm *kvm = filp->private_data;
 		r = kvm->arch.kvm_ops->arch_vm_ioctl(filp, ioctl, arg);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 2fe12b40d503..c1dbdd428025 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1327,6 +1327,7 @@ struct kvm_s390_ucas_mapping {
 #define KVM_PPC_GET_RMMU_INFO	  _IOW(KVMIO,  0xb0, struct kvm_ppc_rmmu_info)
 /* Available with KVM_CAP_PPC_GET_CPU_CHAR */
 #define KVM_PPC_GET_CPU_CHAR	  _IOR(KVMIO,  0xb1, struct kvm_ppc_cpu_char)
+#define KVM_PPC_SVM_OFF		  _IO(KVMIO,  0xb2)
 
 /* ioctl for vm fd */
 #define KVM_CREATE_DEVICE	  _IOWR(KVMIO,  0xe0, struct kvm_create_device)
diff --git a/tools/include/uapi/linux/kvm.h b/tools/include/uapi/linux/kvm.h
index 6d4ea4b6c922..03c89f4a01b2 100644
--- a/tools/include/uapi/linux/kvm.h
+++ b/tools/include/uapi/linux/kvm.h
@@ -1319,6 +1319,7 @@ struct kvm_s390_ucas_mapping {
 #define KVM_PPC_GET_RMMU_INFO	  _IOW(KVMIO,  0xb0, struct kvm_ppc_rmmu_info)
 /* Available with KVM_CAP_PPC_GET_CPU_CHAR */
 #define KVM_PPC_GET_CPU_CHAR	  _IOR(KVMIO,  0xb1, struct kvm_ppc_cpu_char)
+#define KVM_PPC_SVM_OFF		  _IO(KVMIO,  0xb2)
 
 /* ioctl for vm fd */
 #define KVM_CREATE_DEVICE	  _IOWR(KVMIO,  0xe0, struct kvm_create_device)
-- 
2.17.1