Re: [PATCH 09/12] KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl

[Venu Busireddy]

On 2020-02-27 11:57:50 -0600, Venu Busireddy wrote:
> On 2020-02-13 01:17:45 +0000, Ashish Kalra wrote:
> > From: Brijesh Singh <brijesh.singh@xxxxxxx>
> > 
> > The ioctl can be used to retrieve page encryption bitmap for a given
> > gfn range.
> > 
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > Cc: "Radim KrÄmÃÅ" <rkrcmar@xxxxxxxxxx>
> > Cc: Joerg Roedel <joro@xxxxxxxxxx>
> > Cc: Borislav Petkov <bp@xxxxxxx>
> > Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
> > Cc: x86@xxxxxxxxxx
> > Cc: kvm@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> > Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
> 
> This patch does not apply to upstream Linux version 5.5.6.
> 
>   <snip>
>   Applying: KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl
>   error: patch failed: Documentation/virt/kvm/api.txt:4213
>   error: Documentation/virt/kvm/api.txt: patch does not apply
>   error: patch failed: include/uapi/linux/kvm.h:1478
>   error: include/uapi/linux/kvm.h: patch does not apply
>   Patch failed at 0009 KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl
>   <snip>
> 
> Which kernel version does this patch series apply to, cleanly?

Tried git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git.
With that, patch 08/12 fails with the top of that tree, as well as
tag v5.6-rc3.

> Thanks,
> 
> Venu
> 
> > ---
> >  Documentation/virt/kvm/api.txt  | 27 +++++++++++++++++++++
> >  arch/x86/include/asm/kvm_host.h |  2 ++
> >  arch/x86/kvm/svm.c              | 43 +++++++++++++++++++++++++++++++++
> >  arch/x86/kvm/x86.c              | 12 +++++++++
> >  include/uapi/linux/kvm.h        | 12 +++++++++
> >  5 files changed, 96 insertions(+)
> > 
> > diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
> > index c6e1ce5d40de..053aecfabe74 100644
> > --- a/Documentation/virt/kvm/api.txt
> > +++ b/Documentation/virt/kvm/api.txt
> > @@ -4213,6 +4213,33 @@ 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.
> >  
> >  
> > +4.120 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 concept of private and shared pages. The private
> > +page is encrypted with the guest-specific key, while shared page 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 userspace need to use SEV migration commands to transmit
> > +the page.
> > +
> > +
> >  5. The kvm_run structure
> >  ------------------------
> >  
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 4ae7293033b2..a6882c5214b4 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -1258,6 +1258,8 @@ 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_arch_async_pf {
> > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> > index f09791109075..f1c8806a97c6 100644
> > --- a/arch/x86/kvm/svm.c
> > +++ b/arch/x86/kvm/svm.c
> > @@ -7673,6 +7673,48 @@ static int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa,
> >  	return ret;
> >  }
> >  
> > +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;
> > +	unsigned long *bitmap;
> > +	unsigned long sz, i;
> > +	int ret;
> > +
> > +	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) / 8;
> > +	bitmap = kmalloc(sz, GFP_KERNEL);
> > +	if (!bitmap)
> > +		return -ENOMEM;
> > +
> > +	/* by default all pages are marked encrypted */
> > +	memset(bitmap, 0xff, sz);
> > +
> > +	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;
> > @@ -8066,6 +8108,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
> >  	.apic_init_signal_blocked = svm_apic_init_signal_blocked,
> >  
> >  	.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 298627fa3d39..e955f886ee17 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -5213,6 +5213,18 @@ long kvm_arch_vm_ioctl(struct file *filp,
> >  	case KVM_SET_PMU_EVENT_FILTER:
> >  		r = kvm_vm_ioctl_set_pmu_event_filter(kvm, argp);
> >  		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 4e80c57a3182..9377b26c5f4e 100644
> > --- a/include/uapi/linux/kvm.h
> > +++ b/include/uapi/linux/kvm.h
> > @@ -500,6 +500,16 @@ struct kvm_dirty_log {
> >  	};
> >  };
> >  
> > +/* 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;
> > +	};
> > +};
> > +
> >  /* for KVM_CLEAR_DIRTY_LOG */
> >  struct kvm_clear_dirty_log {
> >  	__u32 slot;
> > @@ -1478,6 +1488,8 @@ struct kvm_enc_region {
> >  #define KVM_S390_NORMAL_RESET	_IO(KVMIO,   0xc3)
> >  #define KVM_S390_CLEAR_RESET	_IO(KVMIO,   0xc4)
> >  
> > +#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
> >