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Subject[PATCH 12/12] KVM: x86: Introduce KVM_PAGE_ENC_BITMAP_RESET ioctl
Date
From: Ashish Kalra <ashish.kalra@amd.com>

This ioctl can be used by the application to reset the page
encryption bitmap managed by the KVM driver. A typical usage
for this ioctl is on VM reboot, on reboot, we must reinitialize
the bitmap.

Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
Documentation/virt/kvm/api.txt | 11 +++++++++++
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm.c | 16 ++++++++++++++++
arch/x86/kvm/x86.c | 6 ++++++
include/uapi/linux/kvm.h | 1 +
5 files changed, 35 insertions(+)

diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
index d4e29a457e80..bf0fd3c2ea07 100644
--- a/Documentation/virt/kvm/api.txt
+++ b/Documentation/virt/kvm/api.txt
@@ -4261,6 +4261,17 @@ 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.

+4.122 KVM_PAGE_ENC_BITMAP_RESET (vm ioctl)
+
+Capability: basic
+Architectures: x86
+Type: vm ioctl
+Parameters: none
+Returns: 0 on success, -1 on error
+
+The KVM_PAGE_ENC_BITMAP_RESET is used to reset the guest's page encryption
+bitmap during guest reboot and this is only done on the guest's boot vCPU.
+
5. The kvm_run structure
------------------------

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 698ea92290af..746c9c84d14a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1262,6 +1262,7 @@ struct kvm_x86_ops {
struct kvm_page_enc_bitmap *bmap);
int (*set_page_enc_bitmap)(struct kvm *kvm,
struct kvm_page_enc_bitmap *bmap);
+ int (*reset_page_enc_bitmap)(struct kvm *kvm);
};

struct kvm_arch_async_pf {
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a710a6a2d18c..1659539b1873 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -7756,6 +7756,21 @@ static int svm_set_page_enc_bitmap(struct kvm *kvm,
return ret;
}

+static int svm_reset_page_enc_bitmap(struct kvm *kvm)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+
+ if (!sev_guest(kvm))
+ return -ENOTTY;
+
+ mutex_lock(&kvm->lock);
+ /* by default all pages should be 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;
+}
+
static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
{
struct kvm_sev_cmd sev_cmd;
@@ -8151,6 +8166,7 @@ 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,
+ .reset_page_enc_bitmap = svm_reset_page_enc_bitmap,
};

static int __init svm_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a1ac5b8c5cd7..eeb2a3dfeb02 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5237,6 +5237,12 @@ long kvm_arch_vm_ioctl(struct file *filp,
r = kvm_x86_ops->set_page_enc_bitmap(kvm, &bitmap);
break;
}
+ case KVM_PAGE_ENC_BITMAP_RESET: {
+ r = -ENOTTY;
+ if (kvm_x86_ops->reset_page_enc_bitmap)
+ r = kvm_x86_ops->reset_page_enc_bitmap(kvm);
+ break;
+ }
default:
r = -ENOTTY;
}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 2f36afd11e0e..4001c22cb36b 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1490,6 +1490,7 @@ struct kvm_enc_region {

#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)
+#define KVM_PAGE_ENC_BITMAP_RESET _IO(KVMIO, 0xc4)

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