[PATCH v2 5/9] KVM: x86: Introduce KVM_SET_PAGE_ENC_BITMAP ioctl

Ashish Kalra
2020-12-01T00:48:55Z

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
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
Documentation/virt/kvm/api.rst | 44 +++++++++++++++++++++++++++++
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/svm/sev.c | 50 +++++++++++++++++++++++++++++++++
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, 111 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index ae410f4332ab..1a3336cbbfe8 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4698,6 +4698,28 @@ or shared. The bitmap 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.

+4.126 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
-------------------------
@@ -4852,6 +4874,28 @@ into user space.
If a vCPU is in running state while this ioctl is invoked, the vCPU may
experience inconsistent filtering behavior on MSR accesses.

+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 8c2e40199ecb..352ebc576036 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1286,6 +1286,8 @@ 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_nested_ops {
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index a6586dd29767..e99ea9c711de 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1084,6 +1084,56 @@ 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 bff89cab3ed0..6ebdf20773ea 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4315,6 +4315,7 @@ 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 4ce73f1034b9..2268c0ab650b 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -414,6 +414,7 @@ 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_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);

extern struct kvm_x86_nested_ops svm_nested_ops;

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d3cb95a4dd55..3cf64a94004f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5707,6 +5707,18 @@ 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 d0b9171bdb03..8e1adcd598a8 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1574,6 +1574,7 @@ struct kvm_pv_cmd {
#define KVM_RESET_DIRTY_RINGS _IO(KVMIO, 0xc7)

#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