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Subject[PATCH v10 10/16] KVM: x86: Introduce KVM_GET_SHARED_PAGES_LIST ioctl
Date
From: Brijesh Singh <brijesh.singh@amd.com>

The ioctl is used to retrieve a guest's shared pages list.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Co-developed-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
Documentation/virt/kvm/api.rst | 24 ++++++++++++++++
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/svm/sev.c | 49 +++++++++++++++++++++++++++++++++
arch/x86/kvm/svm/svm.c | 1 +
arch/x86/kvm/svm/svm.h | 1 +
arch/x86/kvm/x86.c | 12 ++++++++
include/uapi/linux/kvm.h | 9 ++++++
7 files changed, 98 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 99ceb978c8b0..59ef537c0cdd 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4677,6 +4677,30 @@ This ioctl resets VCPU registers and control structures according to
the clear cpu reset definition in the POP. However, the cpu is not put
into ESA mode. This reset is a superset of the initial reset.

+4.125 KVM_GET_SHARED_PAGES_LIST (vm ioctl)
+---------------------------------------
+
+:Capability: basic
+:Architectures: x86
+:Type: vm ioctl
+:Parameters: struct kvm_shared_pages_list (in/out)
+:Returns: 0 on success, -1 on error
+
+/* for KVM_GET_SHARED_PAGES_LIST */
+struct kvm_shared_pages_list {
+ int __user *pnents;
+ void __user *buffer;
+ __u32 size;
+};
+
+The encrypted VMs have the concept of private and shared pages. The private
+pages are encrypted with the guest-specific key, while the shared pages may
+be encrypted with the hypervisor key. The KVM_GET_SHARED_PAGES_LIST can
+be used to get guest's shared/unencrypted memory regions list.
+This list can be used during the guest migration. If the page
+is private then the userspace need to use SEV migration commands to transmit
+the page.
+

4.125 KVM_S390_PV_COMMAND
-------------------------
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2da5f5e2a10e..cd354d830e13 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1303,6 +1303,8 @@ struct kvm_x86_ops {
void (*vcpu_deliver_sipi_vector)(struct kvm_vcpu *vcpu, u8 vector);
int (*page_enc_status_hc)(struct kvm *kvm, unsigned long gpa,
unsigned long sz, unsigned long mode);
+ int (*get_shared_pages_list)(struct kvm *kvm,
+ struct kvm_shared_pages_list *list);
};

struct kvm_x86_nested_ops {
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 55c628df5155..701d74c8b15b 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -50,6 +50,11 @@ struct shared_region {
unsigned long gfn_start, gfn_end;
};

+struct shared_region_array_entry {
+ unsigned long gfn_start;
+ unsigned long gfn_end;
+};
+
static int sev_flush_asids(void)
{
int ret, error = 0;
@@ -1622,6 +1627,50 @@ int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa,
return ret;
}

+int svm_get_shared_pages_list(struct kvm *kvm,
+ struct kvm_shared_pages_list *list)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+ struct shared_region_array_entry *array;
+ struct shared_region *pos;
+ int ret, nents = 0;
+ unsigned long sz;
+
+ if (!sev_guest(kvm))
+ return -ENOTTY;
+
+ if (!list->size)
+ return -EINVAL;
+
+ if (!sev->shared_pages_list_count)
+ return put_user(0, list->pnents);
+
+ sz = sev->shared_pages_list_count * sizeof(struct shared_region_array_entry);
+ if (sz > list->size)
+ return -E2BIG;
+
+ array = kmalloc(sz, GFP_KERNEL);
+ if (!array)
+ return -ENOMEM;
+
+ mutex_lock(&kvm->lock);
+ list_for_each_entry(pos, &sev->shared_pages_list, list) {
+ array[nents].gfn_start = pos->gfn_start;
+ array[nents++].gfn_end = pos->gfn_end;
+ }
+ mutex_unlock(&kvm->lock);
+
+ ret = -EFAULT;
+ if (copy_to_user(list->buffer, array, sz))
+ goto out;
+ if (put_user(nents, list->pnents))
+ goto out;
+ ret = 0;
+out:
+ kfree(array);
+ return ret;
+}
+
int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
{
struct kvm_sev_cmd sev_cmd;
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index bb249ec625fc..533ce47ff158 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4538,6 +4538,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
.vcpu_deliver_sipi_vector = svm_vcpu_deliver_sipi_vector,

.page_enc_status_hc = svm_page_enc_status_hc,
+ .get_shared_pages_list = svm_get_shared_pages_list,
};

static struct kvm_x86_init_ops svm_init_ops __initdata = {
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 6437c1fa1f24..6a777c61373c 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -477,6 +477,7 @@ int nested_svm_exit_special(struct vcpu_svm *svm);
void sync_nested_vmcb_control(struct vcpu_svm *svm);
int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa,
unsigned long npages, unsigned long enc);
+int svm_get_shared_pages_list(struct kvm *kvm, struct kvm_shared_pages_list *list);

extern struct kvm_x86_nested_ops svm_nested_ops;

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2f17f0f9ace7..acfec2ae1402 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5719,6 +5719,18 @@ long kvm_arch_vm_ioctl(struct file *filp,
case KVM_X86_SET_MSR_FILTER:
r = kvm_vm_ioctl_set_msr_filter(kvm, argp);
break;
+ case KVM_GET_SHARED_PAGES_LIST: {
+ struct kvm_shared_pages_list list;
+
+ r = -EFAULT;
+ if (copy_from_user(&list, argp, sizeof(list)))
+ goto out;
+
+ r = -ENOTTY;
+ if (kvm_x86_ops.get_shared_pages_list)
+ r = kvm_x86_ops.get_shared_pages_list(kvm, &list);
+ break;
+ }
default:
r = -ENOTTY;
}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index c4e195a4220f..0529ba80498a 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -544,6 +544,13 @@ struct kvm_clear_dirty_log {
};
};

+/* for KVM_GET_SHARED_PAGES_LIST */
+struct kvm_shared_pages_list {
+ int __user *pnents;
+ void __user *buffer;
+ __u32 size;
+};
+
/* for KVM_SET_SIGNAL_MASK */
struct kvm_signal_mask {
__u32 len;
@@ -1565,6 +1572,8 @@ struct kvm_pv_cmd {
/* Available with KVM_CAP_DIRTY_LOG_RING */
#define KVM_RESET_DIRTY_RINGS _IO(KVMIO, 0xc7)

+#define KVM_GET_SHARED_PAGES_LIST _IOW(KVMIO, 0xc8, struct kvm_shared_pages_list)
+
/* Secure Encrypted Virtualization command */
enum sev_cmd_id {
/* Guest initialization commands */
--
2.17.1
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