Re: [PATCH v8 09/18] KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl
On Tue, May 5, 2020 at 2:17 PM Ashish Kalra wrote:
>
> From: Brijesh Singh
>
> The ioctl can be used to retrieve page encryption bitmap for a given
> gfn range.
>
> Return the correct bitmap as per the number of pages being requested
> by the user. Ensure that we only copy bmap->num_pages bytes in the
> userspace buffer, if bmap->num_pages is not byte aligned we read
> the trailing bits from the userspace and copy those bits as is.
>
> Cc: Thomas Gleixner
> Cc: Ingo Molnar
> Cc: "H. Peter Anvin"
> Cc: Paolo Bonzini
> Cc: "Radim Krčmář"
> Cc: Joerg Roedel
> Cc: Borislav Petkov
> Cc: Tom Lendacky
> Cc: x...@kernel.org
> Cc: k...@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Reviewed-by: Venu Busireddy
> Signed-off-by: Brijesh Singh
> Signed-off-by: Ashish Kalra
> ---
> Documentation/virt/kvm/api.rst | 27 +
> arch/x86/include/asm/kvm_host.h | 2 +
> arch/x86/kvm/svm/sev.c | 70 +
> 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| 12 ++
> 7 files changed, 125 insertions(+)
>
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index efbbe570aa9b..ecad84086892 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -4636,6 +4636,33 @@ This ioctl resets VCPU registers and control
> structures according to
> the clear cpu reset definition in the POP. However, the cpu is not put
> into ESA mode. This reset is a superset of the initial reset.
>
> +4.125 KVM_GET_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_GET_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;
> + };
> +};
> +
> +The encrypted VMs have the concept of private and shared pages. The private
> +pages are encrypted with the guest-specific key, while the shared pages may
> +be encrypted with the hypervisor key. The KVM_GET_PAGE_ENC_BITMAP can
> +be used to get the bitmap indicating whether the guest page is private
> +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.
> +
>
> 4.125 KVM_S390_PV_COMMAND
> -
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 4a8ee22f4f5b..9e428befb6a4 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1256,6 +1256,8 @@ struct kvm_x86_ops {
> int (*enable_direct_tlbflush)(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_x86_init_ops {
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index f088467708f0..387045902470 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -1434,6 +1434,76 @@ int svm_page_enc_status_hc(struct kvm *kvm, unsigned
> long gpa,
> return 0;
> }
>
> +int svm_get_page_enc_bitmap(struct kvm *kvm,
> + struct kvm_page_enc_bitmap *bmap)
> +{
> + struct kvm_sev_info *sev = _kvm_svm(kvm)->sev_info;
> + unsigned long gfn_start, gfn_end;
> + unsigned long sz, i, sz_bytes;
> + unsigned long *bitmap;
> + int ret, n;
> +
> + 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) / BITS_PER_BYTE;
> + bitmap = kmalloc(sz, GFP_KERNEL);
> + if (!bitmap)
> + return -ENOMEM;
> +
> + /* by default all pages are marked encrypted */
> + memset(bitmap, 0xff, sz);
> +
> + mutex_lock(>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))
gfn_end is not a size? I believe you want either gfn_end - gfn_start
or bmap->num_pages.
> + clear_bit(i - gfn_start, bitmap);
> + }
> + mutex_unlock(>lock);
> +
> + ret = -EFAULT;
> +
> + n = bmap->num_pages % BITS_PER_BYTE;
> + sz_bytes = ALIGN(bmap->num_pages, BITS_PER_BYTE) / BITS_PER_BYTE;
> +
> + /*
> +* Return the correct bitmap as per
[PATCH v8 09/18] KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl
From: Brijesh Singh
The ioctl can be used to retrieve page encryption bitmap for a given
gfn range.
Return the correct bitmap as per the number of pages being requested
by the user. Ensure that we only copy bmap->num_pages bytes in the
userspace buffer, if bmap->num_pages is not byte aligned we read
the trailing bits from the userspace and copy those bits as is.
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: "H. Peter Anvin"
Cc: Paolo Bonzini
Cc: "Radim Krčmář"
Cc: Joerg Roedel
Cc: Borislav Petkov
Cc: Tom Lendacky
Cc: x...@kernel.org
Cc: k...@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Venu Busireddy
Signed-off-by: Brijesh Singh
Signed-off-by: Ashish Kalra
---
Documentation/virt/kvm/api.rst | 27 +
arch/x86/include/asm/kvm_host.h | 2 +
arch/x86/kvm/svm/sev.c | 70 +
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| 12 ++
7 files changed, 125 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index efbbe570aa9b..ecad84086892 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4636,6 +4636,33 @@ This ioctl resets VCPU registers and control structures
according to
the clear cpu reset definition in the POP. However, the cpu is not put
into ESA mode. This reset is a superset of the initial reset.
+4.125 KVM_GET_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_GET_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;
+ };
+};
+
+The encrypted VMs have the concept of private and shared pages. The private
+pages are encrypted with the guest-specific key, while the shared pages may
+be encrypted with the hypervisor key. The KVM_GET_PAGE_ENC_BITMAP can
+be used to get the bitmap indicating whether the guest page is private
+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.
+
4.125 KVM_S390_PV_COMMAND
-
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4a8ee22f4f5b..9e428befb6a4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1256,6 +1256,8 @@ struct kvm_x86_ops {
int (*enable_direct_tlbflush)(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_x86_init_ops {
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index f088467708f0..387045902470 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1434,6 +1434,76 @@ int svm_page_enc_status_hc(struct kvm *kvm, unsigned
long gpa,
return 0;
}
+int svm_get_page_enc_bitmap(struct kvm *kvm,
+ struct kvm_page_enc_bitmap *bmap)
+{
+ struct kvm_sev_info *sev = _kvm_svm(kvm)->sev_info;
+ unsigned long gfn_start, gfn_end;
+ unsigned long sz, i, sz_bytes;
+ unsigned long *bitmap;
+ int ret, n;
+
+ 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) / BITS_PER_BYTE;
+ bitmap = kmalloc(sz, GFP_KERNEL);
+ if (!bitmap)
+ return -ENOMEM;
+
+ /* by default all pages are marked encrypted */
+ memset(bitmap, 0xff, sz);
+
+ mutex_lock(>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(>lock);
+
+ ret = -EFAULT;
+
+ n = bmap->num_pages % BITS_PER_BYTE;
+ sz_bytes = ALIGN(bmap->num_pages, BITS_PER_BYTE) / BITS_PER_BYTE;
+
+ /*
+* Return the correct bitmap as per the number of pages being
+* requested by the user. Ensure that we only copy bmap->num_pages
+* bytes in the userspace buffer, if bmap->num_pages is not byte
+* aligned we read the trailing bits from the userspace and copy
+* those bits as is.
+*/
+
+ if (n) {
+ unsigned char *bitmap_kernel = (unsigned char *)bitmap;
+
