Date:   Wed, 8 Feb 2023 23:25:29 -0800
From:   Isaku Yamahata <isaku.yamahata@gmail.com>
To:     Chao Peng <chao.p.peng@linux.intel.com>
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
        linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
        linux-doc@vger.kernel.org, qemu-devel@nongnu.org,
        Paolo Bonzini <pbonzini@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Arnd Bergmann <arnd@arndb.de>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Miaohe Lin <linmiaohe@huawei.com>, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>, Hugh Dickins <hughd@google.com>,
        Jeff Layton <jlayton@kernel.org>,
        "J . Bruce Fields" <bfields@fieldses.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Shuah Khan <shuah@kernel.org>, Mike Rapoport <rppt@kernel.org>,
        Steven Price <steven.price@arm.com>,
        "Maciej S . Szmigiero" <mail@maciej.szmigiero.name>,
        Vlastimil Babka <vbabka@suse.cz>,
        Vishal Annapurve <vannapurve@google.com>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
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        luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com,
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        Quentin Perret <qperret@google.com>, tabba@google.com,
        Michael Roth <michael.roth@amd.com>, mhocko@suse.com,
        wei.w.wang@intel.com, isaku.yamahata@gmail.com
Subject: Re: [PATCH v10 2/9] KVM: Introduce per-page memory attributes
Message-ID: <20230209072529.GB4175971@ls.amr.corp.intel.com>
References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com>
 <20221202061347.1070246-3-chao.p.peng@linux.intel.com>
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On Fri, Dec 02, 2022 at 02:13:40PM +0800,
Chao Peng <chao.p.peng@linux.intel.com> wrote:

> +static int kvm_vm_ioctl_set_mem_attributes(struct kvm *kvm,
> +					   struct kvm_memory_attributes *attrs)
> +{
> +	gfn_t start, end;
> +	unsigned long i;
> +	void *entry;
> +	u64 supported_attrs = kvm_supported_mem_attributes(kvm);
> +
> +	/* flags is currently not used. */
> +	if (attrs->flags)
> +		return -EINVAL;
> +	if (attrs->attributes & ~supported_attrs)
> +		return -EINVAL;
> +	if (attrs->size == 0 || attrs->address + attrs->size < attrs->address)
> +		return -EINVAL;
> +	if (!PAGE_ALIGNED(attrs->address) || !PAGE_ALIGNED(attrs->size))
> +		return -EINVAL;
> +
> +	start = attrs->address >> PAGE_SHIFT;
> +	end = (attrs->address + attrs->size - 1 + PAGE_SIZE) >> PAGE_SHIFT;
> +
> +	entry = attrs->attributes ? xa_mk_value(attrs->attributes) : NULL;
> +
> +	mutex_lock(&kvm->lock);
> +	for (i = start; i < end; i++)
> +		if (xa_err(xa_store(&kvm->mem_attr_array, i, entry,
> +				    GFP_KERNEL_ACCOUNT)))
> +			break;
> +	mutex_unlock(&kvm->lock);
> +
> +	attrs->address = i << PAGE_SHIFT;
> +	attrs->size = (end - i) << PAGE_SHIFT;
> +
> +	return 0;
> +}
> +#endif /* CONFIG_HAVE_KVM_MEMORY_ATTRIBUTES */
> +

If memslot isn't private, it should return error if private attribute is set.
Something like following check is needed.

+       if (attrs->flags & KVM_MEM_PRIVATE) {
+               /* non-private memory slot doesn't allow KVM_MEM_PRIVATE */
+               for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) {
+                       struct kvm_memslot_iter iter;
+                       struct kvm_memslots *slots;
+
+                       slots = __kvm_memslots(kvm, i);
+                       kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) {
+                               if (!kvm_slot_can_be_private(iter.slot)) {
+                                       mutex_unlock(&kvm->slots_lock);
+                                       return -EINVAL;
+                               }
+                       }
+               }
+       }
+


-- 
Isaku Yamahata <isaku.yamahata@gmail.com>