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Subject[PATCH 11/12] KVM: x86: Introduce KVM_SET_PAGE_ENC_BITMAP ioctl
Date
From: Brijesh Singh <brijesh.singh@amd.com>

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

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>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
Documentation/virt/kvm/api.txt | 21 +++++++++++++++++
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/svm.c | 42 +++++++++++++++++++++++++++++++++
arch/x86/kvm/x86.c | 12 ++++++++++
include/uapi/linux/kvm.h | 1 +
5 files changed, 78 insertions(+)

diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
index 053aecfabe74..d4e29a457e80 100644
--- a/Documentation/virt/kvm/api.txt
+++ b/Documentation/virt/kvm/api.txt
@@ -4239,6 +4239,27 @@ 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.

+4.121 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 a6882c5214b4..698ea92290af 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1260,6 +1260,8 @@ 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_arch_async_pf {
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f1c8806a97c6..a710a6a2d18c 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -7715,6 +7715,47 @@ static int svm_get_page_enc_bitmap(struct kvm *kvm,
return ret;
}

+static 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, i;
+ int ret;
+
+ if (!sev_guest(kvm))
+ return -ENOTTY;
+
+ 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;
+
+ i = gfn_start;
+ for_each_clear_bit_from(i, bitmap, (gfn_end - gfn_start))
+ clear_bit(i + gfn_start, sev->page_enc_bmap);
+
+ ret = 0;
+unlock:
+ mutex_unlock(&kvm->lock);
+out:
+ kfree(bitmap);
+ return ret;
+}
+
static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
{
struct kvm_sev_cmd sev_cmd;
@@ -8109,6 +8150,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {

.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 int __init svm_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e955f886ee17..a1ac5b8c5cd7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5225,6 +5225,18 @@ 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 9377b26c5f4e..2f36afd11e0e 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1489,6 +1489,7 @@ struct kvm_enc_region {
#define KVM_S390_CLEAR_RESET _IO(KVMIO, 0xc4)

#define KVM_GET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc2, struct kvm_page_enc_bitmap)
+#define KVM_SET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc3, struct kvm_page_enc_bitmap)

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