[PATCH v11 6/7] KVM: PPC: Support reset of secure guest

Bharata B Rao
2019-11-25T03:18:30Z

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:

- Release all device pages of the secure guest.
- 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.
- Reinit the partition scoped page tables

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]
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
[Prevent any vpus from running when unpinng VPAs]
---
Documentation/virt/kvm/api.txt | 18 +++++
arch/powerpc/include/asm/kvm_ppc.h | 1 +
arch/powerpc/include/asm/ultravisor-api.h | 1 +
arch/powerpc/include/asm/ultravisor.h | 5 ++
arch/powerpc/kvm/book3s_hv.c | 90 +++++++++++++++++++++++
arch/powerpc/kvm/powerpc.c | 12 +++
include/uapi/linux/kvm.h | 1 +
7 files changed, 128 insertions(+)

diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
index 4833904d32a5..5a773bd3e686 100644
--- a/Documentation/virt/kvm/api.txt
+++ b/Documentation/virt/kvm/api.txt
@@ -4126,6 +4126,24 @@ 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 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..3713e8e4d7ea 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -321,6 +321,7 @@ 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..a0bc1722dec1 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -5000,6 +5000,7 @@ 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 +5443,94 @@ static int kvmhv_store_to_eaddr(struct kvm_vcpu *vcpu, ulong *eaddr, void *ptr,
return rc;
}

+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;
+}
+
+/*
+ * IOCTL handler to turn off secure mode of guest
+ *
+ * - Release all device pages
+ * - Issue ucall to terminate the guest on the UV side
+ * - Unpin the VPA pages.
+ * - Reinit the partition scoped page tables
+ */
+static int kvmhv_svm_off(struct kvm *kvm)
+{
+ struct kvm_vcpu *vcpu;
+ int mmu_was_ready;
+ int srcu_idx;
+ int ret = 0;
+ int i;
+
+ if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))
+ return ret;
+
+ mutex_lock(&kvm->arch.mmu_setup_lock);
+ mmu_was_ready = kvm->arch.mmu_ready;
+ if (kvm->arch.mmu_ready) {
+ kvm->arch.mmu_ready = 0;
+ /* order mmu_ready vs. vcpus_running */
+ smp_mb();
+ if (atomic_read(&kvm->arch.vcpus_running)) {
+ kvm->arch.mmu_ready = 1;
+ ret = -EBUSY;
+ goto out;
+ }
+ }
+
+ 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);
+ 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;
+ }
+
+ /*
+ * When secure guest is reset, all the guest pages are sent
+ * to UV via UV_PAGE_IN before the non-boot vcpus get a
+ * chance to run and unpin their VPA pages. Unpinning of all
+ * VPA pages is done here explicitly so that VPA pages
+ * can be migrated to the secure side.
+ *
+ * This is required to for the secure SMP guest to reboot
+ * correctly.
+ */
+ 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);
+ }
+
+ kvmppc_setup_partition_table(kvm);
+ kvm->arch.secure_guest = 0;
+ kvm->arch.mmu_ready = mmu_was_ready;
+out:
+ mutex_unlock(&kvm->arch.mmu_setup_lock);
+ 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 +5573,7 @@ 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/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