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

[Ashish Kalra <ashish.kalra@amd.com>]

The patch series should apply to tag v5.6-rc1.

I will be posting the v5 of this patchset next week, which should
apply on top of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git.

Thanks,
Ashish

On Thu, Feb 27, 2020 at 12:18:58PM -0600, Venu Busireddy wrote:
> 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@amd.com>
> > > 
> > > The ioctl can be used to retrieve page encryption bitmap for a given
> > > gfn range.
> > > 
> > > 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>
> > > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
> > 
> > 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
> > >