Re: [PATCH v6 12/14] KVM: x86: Introduce KVM_PAGE_ENC_BITMAP_RESET ioctl
From: Krish Sadhukhan
Date: Mon Apr 06 2020 - 14:53:30 EST
On 4/3/20 2:45 PM, Ashish Kalra wrote:
On Fri, Apr 03, 2020 at 02:14:23PM -0700, Krish Sadhukhan wrote:
On 3/29/20 11:23 PM, Ashish Kalra wrote:
From: Ashish Kalra <ashish.kalra@xxxxxxx>
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@xxxxxxx>
---
Documentation/virt/kvm/api.rst | 13 +++++++++++++
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, 37 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 4d1004a154f6..a11326ccc51d 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4698,6 +4698,19 @@ 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.
+4.127 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 d30f770aaaea..a96ef6338cd2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1273,6 +1273,7 @@ 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 313343a43045..c99b0207a443 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -7797,6 +7797,21 @@ 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;
@@ -8203,6 +8218,7 @@ 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,
We don't need to initialize the intel ops to NULL ? It's not initialized in
the previous patch either.
};
This struct is declared as "static storage", so won't the non-initialized
members be 0 ?
Correct. Although, I see that 'nested_enable_evmcs' is explicitly
initialized. We should maintain the convention, perhaps.
static int __init svm_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 05e953b2ec61..2127ed937f53 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5250,6 +5250,12 @@ 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 b4b01d47e568..0884a581fc37 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, 0xc5, struct kvm_page_enc_bitmap)
#define KVM_SET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc6, struct kvm_page_enc_bitmap)
+#define KVM_PAGE_ENC_BITMAP_RESET _IO(KVMIO, 0xc7)
/* Secure Encrypted Virtualization command */
enum sev_cmd_id {
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>