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Subject[RFC PATCH v1 09/10] KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl
Date
The ioctl can be used to retrieve page encryption bitmap for a given
kvm memory slot.

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>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm.c | 54 ++++++++++++++++++++++++++++++++-
arch/x86/kvm/x86.c | 12 ++++++++
include/uapi/linux/kvm.h | 12 ++++++++
4 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index adb0ca035b97..9947c4be825d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1198,6 +1198,7 @@ struct kvm_x86_ops {
bool (*need_emulation_on_page_fault)(struct kvm_vcpu *vcpu);
int (*page_enc_status_hc)(struct kvm *kvm, unsigned long gpa,
unsigned long sz, unsigned long mode);
+ int (*get_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 f024f208b052..f386d72c929b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -7437,6 +7437,57 @@ static int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa,
return r;
}

+static int svm_get_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;
+ struct kvm_memory_slot *memslot;
+ struct kvm_memslots *slots;
+ unsigned long *bitmap;
+ unsigned long sz, i;
+ int ret, as_id, id;
+
+ if (!sev_guest(kvm))
+ return -ENOTTY;
+
+ as_id = bmap->slot >> 16;
+ id = (u16)bmap->slot;
+ if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
+ return -EINVAL;
+
+ slots = __kvm_memslots(kvm, as_id);
+ memslot = id_to_memslot(slots, id);
+
+ gfn_start = memslot->base_gfn;
+ gfn_end = gfn_start + memslot->npages;
+
+ sz = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+ bitmap = kmalloc(sz, GFP_KERNEL);
+ if (!bitmap)
+ return -ENOMEM;
+
+ memset(bitmap, 0xff, sz); /* by default all pages are marked encrypted */
+
+ mutex_lock(&kvm->lock);
+ if (sev->page_enc_bmap) {
+ i = gfn_start;
+ for_each_clear_bit_from(i, sev->page_enc_bmap,
+ min(sev->page_enc_bmap_size, gfn_end))
+ clear_bit(i - gfn_start, bitmap);
+ }
+ mutex_unlock(&kvm->lock);
+
+ ret = -EFAULT;
+ if (copy_to_user(bmap->enc_bitmap, bitmap, sz))
+ goto out;
+
+ ret = 0;
+out:
+ kfree(bitmap);
+ return ret;
+}
+
static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
{
struct kvm_sev_cmd sev_cmd;
@@ -7779,7 +7830,8 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {

.need_emulation_on_page_fault = svm_need_emulation_on_page_fault,

- .page_enc_status_hc = svm_page_enc_status_hc
+ .page_enc_status_hc = svm_page_enc_status_hc,
+ .get_page_enc_bitmap = svm_get_page_enc_bitmap
};

static int __init svm_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dea644be5992..44079979b1c5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4882,6 +4882,18 @@ long kvm_arch_vm_ioctl(struct file *filp,
r = kvm_vm_ioctl_hv_eventfd(kvm, &hvevfd);
break;
}
+ case KVM_GET_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->get_page_enc_bitmap)
+ r = kvm_x86_ops->get_page_enc_bitmap(kvm, &bitmap);
+ break;
+ }
default:
r = -ENOTTY;
}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 07e058a3ec11..7f944d4e252c 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -492,6 +492,16 @@ struct kvm_dirty_log {
};
};

+/* for KVM_GET_PAGE_ENC_BITMAP */
+struct kvm_page_enc_bitmap {
+ __u32 slot;
+ __u32 padding1;
+ union {
+ void __user *enc_bitmap; /* one bit per page */
+ __u64 padding2;
+ };
+};
+
/* for KVM_CLEAR_DIRTY_LOG */
struct kvm_clear_dirty_log {
__u32 slot;
@@ -1440,6 +1450,8 @@ struct kvm_enc_region {
/* Available with KVM_CAP_HYPERV_CPUID */
#define KVM_GET_SUPPORTED_HV_CPUID _IOWR(KVMIO, 0xc1, struct kvm_cpuid2)

+#define KVM_GET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc2, struct kvm_page_enc_bitmap)
+
/* Secure Encrypted Virtualization command */
enum sev_cmd_id {
/* Guest initialization commands */
--
2.17.1
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