linux-kernel - Re: [RFC PATCH 2/9] kvm.h: introduce KVM_SET_USER_MEMORY_REGION

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Message-ID: <bb82895c-31bc-67af-d82d-c9342c665755@redhat.com>
Date:   Wed, 28 Sep 2022 18:42:01 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Emanuele Giuseppe Esposito <eesposit@...hat.com>,
        kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        David Hildenbrand <david@...hat.com>,
        Maxim Levitsky <mlevitsk@...hat.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/9] kvm.h: introduce KVM_SET_USER_MEMORY_REGION_LIST
 ioctl

On 9/9/22 12:44, Emanuele Giuseppe Esposito wrote:
> This IOCTL enables atomic update of multiple memslots.
> The userspace application provides a kvm_userspace_memory_region_list
> containing a list of entries, each representing a modification to be
> performed to a memslot.
> 
> Requests with invalidate_slot == 1 are pre-processed, because they
> are ther DELETE or MOVE, and therefore the memslot must be first
> replaced with a copy marked as KVM_MEMSLOT_INVALID, and then replaced.
> 
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@...hat.com>
> ---
>   include/uapi/linux/kvm.h | 21 ++++++++++++++++++++-
>   1 file changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index a36e78710382..673496b91a25 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -103,6 +103,24 @@ struct kvm_userspace_memory_region {
>   	__u64 userspace_addr; /* start of the userspace allocated memory */
>   };
>   
> +/* for KVM_SET_USER_MEMORY_REGION_LIST */
> +struct kvm_userspace_memory_region_entry {
> +	__u32 slot;
> +	__u32 flags;
> +	__u64 guest_phys_addr;
> +	__u64 memory_size; /* bytes */
> +	__u64 userspace_addr; /* start of the userspace allocated memory */
> +	__u8 invalidate_slot;
> +	__u8 padding[31];
> +};
> +
> +/* for KVM_SET_USER_MEMORY_REGION_LIST */
> +struct kvm_userspace_memory_region_list {
> +	__u32 nent;
> +	__u32 flags;
> +	struct kvm_userspace_memory_region_entry entries[0];
> +};
> +
>   /*
>    * The bit 0 ~ bit 15 of kvm_memory_region::flags are visible for userspace,
>    * other bits are reserved for kvm internal use which are defined in
> @@ -1444,7 +1462,8 @@ struct kvm_vfio_spapr_tce {
>   					struct kvm_userspace_memory_region)
>   #define KVM_SET_TSS_ADDR          _IO(KVMIO,   0x47)
>   #define KVM_SET_IDENTITY_MAP_ADDR _IOW(KVMIO,  0x48, __u64)
> -
> +#define KVM_SET_USER_MEMORY_REGION_LIST _IOW(KVMIO, 0x49, \
> +					struct kvm_userspace_memory_region_list)
>   /* enable ucontrol for s390 */
>   struct kvm_s390_ucas_mapping {
>   	__u64 user_addr;

Looks good; however, in the non-RFC I suggest adding documentation in 
this patch already (so no Reviewed-by yet).

Paolo