[PATCH v7 12/18] KVM: x86: Introduce KVM_SET_PAGE_ENC_BITMAP ioctl

From: Ashish Kalra
Date: Thu Apr 30 2020 - 04:45:54 EST

From: Brijesh Singh <Brijesh.Singh@xxxxxxx>

The ioctl can be used to set page encryption bitmap for an
incoming guest.

Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Radim KrÄmÃÅ" <rkrcmar@xxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Reviewed-by: Venu Busireddy <venu.busireddy@xxxxxxxxxx>
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
---
Documentation/virt/kvm/api.rst | 44 ++++++++++++++++++++++++++++++
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/svm/sev.c | 48 +++++++++++++++++++++++++++++++++
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 | 1 +
7 files changed, 109 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index e2f0dd105b5c..56c934db2a96 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4663,6 +4663,28 @@ or shared. The bitmap can be used during the guest migration, if the page
is private then userspace need to use SEV migration commands to transmit
the page.

+4.126 KVM_SET_PAGE_ENC_BITMAP (vm ioctl)
+---------------------------------------
+
+:Capability: basic
+:Architectures: x86
+:Type: vm ioctl
+:Parameters: struct kvm_page_enc_bitmap (in/out)
+:Returns: 0 on success, -1 on error
+
+/* for KVM_SET_PAGE_ENC_BITMAP */
+struct kvm_page_enc_bitmap {
+ __u64 start_gfn;
+ __u64 num_pages;
+ union {
+ void __user *enc_bitmap; /* one bit per page */
+ __u64 padding2;
+ };
+};
+
+During the guest live migration the outgoing guest exports its page encryption
+bitmap, the KVM_SET_PAGE_ENC_BITMAP can be used to build the page encryption
+bitmap for an incoming guest.

4.125 KVM_S390_PV_COMMAND
-------------------------
@@ -4717,6 +4739,28 @@ KVM_PV_VM_VERIFY
Verify the integrity of the unpacked image. Only if this succeeds,
KVM is allowed to start protected VCPUs.

+4.126 KVM_SET_PAGE_ENC_BITMAP (vm ioctl)
+---------------------------------------
+
+:Capability: basic
+:Architectures: x86
+:Type: vm ioctl
+:Parameters: struct kvm_page_enc_bitmap (in/out)
+:Returns: 0 on success, -1 on error
+
+/* for KVM_SET_PAGE_ENC_BITMAP */
+struct kvm_page_enc_bitmap {
+ __u64 start_gfn;
+ __u64 num_pages;
+ union {
+ void __user *enc_bitmap; /* one bit per page */
+ __u64 padding2;
+ };
+};
+
+During the guest live migration the outgoing guest exports its page encryption
+bitmap, the KVM_SET_PAGE_ENC_BITMAP can be used to build the page encryption
+bitmap for an incoming guest.

5. The kvm_run structure
========================
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9e428befb6a4..fc74144d5ab0 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1258,6 +1258,8 @@ struct kvm_x86_ops {
unsigned long sz, unsigned long mode);
int (*get_page_enc_bitmap)(struct kvm *kvm,
struct kvm_page_enc_bitmap *bmap);
+ int (*set_page_enc_bitmap)(struct kvm *kvm,
+ struct kvm_page_enc_bitmap *bmap);
};

struct kvm_x86_init_ops {
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 73bbbffb3487..64ff51ec4933 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1504,6 +1504,54 @@ int svm_get_page_enc_bitmap(struct kvm *kvm,
return ret;
}

+int svm_set_page_enc_bitmap(struct kvm *kvm,
+ struct kvm_page_enc_bitmap *bmap)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+ unsigned long gfn_start, gfn_end;
+ unsigned long *bitmap;
+ unsigned long sz;
+ int ret;
+
+ if (!sev_guest(kvm))
+ return -ENOTTY;
+ /* special case of resetting the complete bitmap */
+ if (!bmap->enc_bitmap) {
+ mutex_lock(&kvm->lock);
+ /* by default all pages are marked encrypted */
+ if (sev->page_enc_bmap_size)
+ bitmap_fill(sev->page_enc_bmap, sev->page_enc_bmap_size);
+ mutex_unlock(&kvm->lock);
+ return 0;
+ }
+
+ gfn_start = bmap->start_gfn;
+ gfn_end = gfn_start + bmap->num_pages;
+
+ sz = ALIGN(bmap->num_pages, BITS_PER_LONG) / 8;
+ bitmap = kmalloc(sz, GFP_KERNEL);
+ if (!bitmap)
+ return -ENOMEM;
+
+ ret = -EFAULT;
+ if (copy_from_user(bitmap, bmap->enc_bitmap, sz))
+ goto out;
+
+ mutex_lock(&kvm->lock);
+ ret = sev_resize_page_enc_bitmap(kvm, gfn_end);
+ if (ret)
+ goto unlock;
+
+ bitmap_copy(sev->page_enc_bmap + BIT_WORD(gfn_start), bitmap, (gfn_end - gfn_start));
+
+ ret = 0;
+unlock:
+ mutex_unlock(&kvm->lock);
+out:
+ kfree(bitmap);
+ 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 588709a9f68e..501e82f5593c 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4017,6 +4017,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {

.page_enc_status_hc = svm_page_enc_status_hc,
.get_page_enc_bitmap = svm_get_page_enc_bitmap,
+ .set_page_enc_bitmap = svm_set_page_enc_bitmap,
};

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 f087fa7b380c..2ebdcce50312 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -405,6 +405,7 @@ int nested_svm_exit_special(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_page_enc_bitmap(struct kvm *kvm, struct kvm_page_enc_bitmap *bmap);
+int svm_set_page_enc_bitmap(struct kvm *kvm, struct kvm_page_enc_bitmap *bmap);

/* avic.c */

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 937797cfaf9a..c4166d7a0493 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5220,6 +5220,18 @@ long kvm_arch_vm_ioctl(struct file *filp,
r = kvm_x86_ops.get_page_enc_bitmap(kvm, &bitmap);
break;
}
+ case KVM_SET_PAGE_ENC_BITMAP: {
+ struct kvm_page_enc_bitmap bitmap;
+
+ r = -EFAULT;
+ if (copy_from_user(&bitmap, argp, sizeof(bitmap)))
+ goto out;
+
+ r = -ENOTTY;
+ if (kvm_x86_ops.set_page_enc_bitmap)
+ r = kvm_x86_ops.set_page_enc_bitmap(kvm, &bitmap);
+ break;
+ }
default:
r = -ENOTTY;
}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index af62f2afaa5d..2798b17484d0 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1529,6 +1529,7 @@ struct kvm_pv_cmd {
#define KVM_S390_PV_COMMAND _IOWR(KVMIO, 0xc5, struct kvm_pv_cmd)

#define KVM_GET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc6, struct kvm_page_enc_bitmap)
+#define KVM_SET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc7, struct kvm_page_enc_bitmap)

/* Secure Encrypted Virtualization command */
enum sev_cmd_id {
--
2.17.1