[PATCH v10 6/8] KVM: PPC: Support reset of secure guest

Bharata B Rao
2019-11-04T04:29:58Z

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 includes the
the following steps:

- Ask UV to terminate the guest via UV_SVM_TERMINATE ucall
- Unpin the VPA pages so that they can be migrated back to secure
side when guest becomes secure again. This is required because
pinned pages can't be migrated.
- Reinitialize guest's partitioned scoped page tables. These are
freed when guest becomes secure (H_SVM_INIT_DONE)
- Release all device 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 <bharata@linux.ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
[Implementation of uv_svm_terminate() and its call from
guest shutdown path]
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
[Unpinning of VPA pages]
---
Documentation/virt/kvm/api.txt | 19 +++++
arch/powerpc/include/asm/kvm_ppc.h | 2 +
arch/powerpc/include/asm/ultravisor-api.h | 1 +
arch/powerpc/include/asm/ultravisor.h | 5 ++
arch/powerpc/kvm/book3s_hv.c | 88 +++++++++++++++++++++++
arch/powerpc/kvm/book3s_hv_uvmem.c | 6 ++
arch/powerpc/kvm/powerpc.c | 12 ++++
include/uapi/linux/kvm.h | 1 +
8 files changed, 134 insertions(+)

diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
index 4833904d32a5..1b2e1d2002ba 100644
--- a/Documentation/virt/kvm/api.txt
+++ b/Documentation/virt/kvm/api.txt
@@ -4126,6 +4126,25 @@ Valid values for 'action':
#define KVM_PMU_EVENT_ALLOW 0
#define KVM_PMU_EVENT_DENY 1

+4.121 KVM_PPC_SVM_OFF
+
+Capability: basic
+Architectures: powerpc
+Type: vm ioctl
+Parameters: none
+Returns: 0 on successful completion,
+Errors:
+ EINVAL: if ultravisor failed to terminate the secure guest
+ ENOMEM: if hypervisor failed to allocate new radix page tables for guest
+
+This ioctl is used to turn off the secure mode of the guest or transition
+the guest from secure mode to normal mode. This is invoked when the guest
+is reset. This has no effect if called for a normal guest.
+
+This ioctl issues an ultravisor call to terminate the secure guest,
+unpins the VPA pages, reinitializes guest's partition scoped page
+tables and releases all the device pages that are used to track the
+secure pages by hypervisor.

5. The kvm_run structure
------------------------
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index ee62776e5433..6d1bb597fe95 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -177,6 +177,7 @@ 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);
+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);
@@ -321,6 +322,7 @@ 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;
diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h
index 4b0d044caa2a..b66f6db7be6c 100644
--- a/arch/powerpc/include/asm/ultravisor-api.h
+++ b/arch/powerpc/include/asm/ultravisor-api.h
@@ -34,5 +34,6 @@
#define UV_UNSHARE_PAGE 0xF134
#define UV_UNSHARE_ALL_PAGES 0xF140
#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 b8e59b7b4ac8..790b0e63681f 100644
--- a/arch/powerpc/include/asm/ultravisor.h
+++ b/arch/powerpc/include/asm/ultravisor.h
@@ -77,4 +77,9 @@ static inline int uv_page_inval(u64 lpid, u64 gpa, u64 page_shift)
return ucall_norets(UV_PAGE_INVAL, lpid, gpa, page_shift);
}

+static inline int uv_svm_terminate(u64 lpid)
+{
+ return ucall_norets(UV_SVM_TERMINATE, lpid);
+}
+
#endif /* _ASM_POWERPC_ULTRAVISOR_H */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index cb7ae1e9e4f2..d2bc4e9bbe7e 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2443,6 +2443,15 @@ static void unpin_vpa(struct kvm *kvm, struct kvmppc_vpa *vpa)
vpa->dirty);
}

+static void unpin_vpa_reset(struct kvm *kvm, struct kvmppc_vpa *vpa)
+{
+ unpin_vpa(kvm, vpa);
+ vpa->gpa = 0;
+ vpa->pinned_addr = NULL;
+ vpa->dirty = false;
+ vpa->update_pending = 0;
+}
+
static void kvmppc_core_vcpu_free_hv(struct kvm_vcpu *vcpu)
{
spin_lock(&vcpu->arch.vpa_update_lock);
@@ -4611,6 +4620,25 @@ 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;
+
+ if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE))
+ return 0;
+
+ 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->arch.mmu_setup_lock held.
@@ -5000,6 +5028,7 @@ 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);
}

@@ -5442,6 +5471,64 @@ static int kvmhv_store_to_eaddr(struct kvm_vcpu *vcpu, ulong *eaddr, void *ptr,
return rc;
}

+/*
+ * IOCTL handler to turn off secure mode of guest
+ *
+ * - Issue ucall to terminate the guest on the UV side
+ * - Unpin the VPA pages (Enables these pages to be migrated back
+ * when VM becomes secure again)
+ * - Recreate partition table as the guest is transitioning back to
+ * normal mode
+ * - Release all device pages
+ */
+static int kvmhv_svm_off(struct kvm *kvm)
+{
+ struct kvm_vcpu *vcpu;
+ int srcu_idx;
+ int ret = 0;
+ int i;
+
+ if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))
+ return ret;
+
+ srcu_idx = srcu_read_lock(&kvm->srcu);
+ for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+ struct kvm_memory_slot *memslot;
+ struct kvm_memslots *slots = __kvm_memslots(kvm, i);
+
+ if (!slots)
+ continue;
+
+ kvm_for_each_memslot(memslot, slots) {
+ kvmppc_uvmem_drop_pages(memslot, kvm, true);
+ uv_unregister_mem_slot(kvm->arch.lpid, memslot->id);
+ }
+ }
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
+
+ ret = uv_svm_terminate(kvm->arch.lpid);
+ if (ret != U_SUCCESS) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ spin_lock(&vcpu->arch.vpa_update_lock);
+ unpin_vpa_reset(kvm, &vcpu->arch.dtl);
+ unpin_vpa_reset(kvm, &vcpu->arch.slb_shadow);
+ unpin_vpa_reset(kvm, &vcpu->arch.vpa);
+ spin_unlock(&vcpu->arch.vpa_update_lock);
+ }
+
+ ret = kvmppc_reinit_partition_table(kvm);
+ if (ret)
+ goto out;
+
+ kvm->arch.secure_guest = 0;
+out:
+ return ret;
+}
+
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,
@@ -5484,6 +5571,7 @@ 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_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 6f26a0351a31..2df0d3f80c60 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -93,6 +93,7 @@
#include <linux/ksm.h>
#include <asm/ultravisor.h>
#include <asm/mman.h>
+#include <asm/kvm_ppc.h>

static struct dev_pagemap kvmppc_uvmem_pgmap;
static unsigned long *kvmppc_uvmem_bitmap;
@@ -237,6 +238,11 @@ unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)
if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))
return H_UNSUPPORTED;

+ if (kvm_is_radix(kvm)) {
+ kvmppc_free_radix(kvm);
+ pr_info("LPID %d went secure, freed HV side radix pgtables\n",
+ kvm->arch.lpid);
+ }
kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE;
return H_SUCCESS;
}
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 3a77bb643452..ec9713c1d928 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -31,6 +31,8 @@
#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"
@@ -2411,6 +2413,16 @@ 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 52641d8ca9e8..efa8ad88cbd2 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1337,6 +1337,7 @@ struct kvm_s390_ucas_mapping {
#define KVM_PPC_GET_CPU_CHAR _IOR(KVMIO, 0xb1, struct kvm_ppc_cpu_char)
/* Available with KVM_CAP_PMU_EVENT_FILTER */
#define KVM_SET_PMU_EVENT_FILTER _IOW(KVMIO, 0xb2, struct kvm_pmu_event_filter)
+#define KVM_PPC_SVM_OFF _IO(KVMIO, 0xb3)

/* ioctl for vm fd */
#define KVM_CREATE_DEVICE _IOWR(KVMIO, 0xe0, struct kvm_create_device)
--
2.21.0