linux-kernel - Re: [PATCH v10 060/108] KVM: Add functions to set GFN to private or shared

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Message-ID: <20221103020154.GD954260@ls.amr.corp.intel.com>
Date:   Wed, 2 Nov 2022 19:01:54 -0700
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     Xiaoyao Li <xiaoyao.li@...el.com>
Cc:     isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>, erdemaktas@...gle.com,
        Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>,
        David Matlack <dmatlack@...gle.com>
Subject: Re: [PATCH v10 060/108] KVM: Add functions to set GFN to private or
 shared

On Tue, Nov 01, 2022 at 06:21:26PM +0800,
Xiaoyao Li <xiaoyao.li@...el.com> wrote:

> On 10/30/2022 2:23 PM, isaku.yamahata@...el.com wrote:
> > From: Isaku Yamahata <isaku.yamahata@...el.com>
> > 
> > TDX KVM support needs to track whether GFN is private or shared.  Introduce
> > functions to set whether GFN is private or shared and pre-allocate memory
> > for xarray.
> > 
> > Suggested-by: Sean Christopherson <seanjc@...gle.com>
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> > ---
> >   include/linux/kvm_host.h | 11 ++++++
> >   virt/kvm/kvm_main.c      | 74 ++++++++++++++++++++++++++++++++++++++++
> >   2 files changed, 85 insertions(+)
> > 
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index a0b64308d240..fac07886ab39 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -2307,9 +2307,20 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr)
> >   #define KVM_MEM_ATTR_PRIVATE	0x0002
> >   #ifdef __KVM_HAVE_ARCH_UPDATE_MEM_ATTR
> > +/* memory attr on [start, end) */
> > +int kvm_vm_reserve_mem_attr(struct kvm *kvm, gfn_t start, gfn_t end);
> > +int kvm_vm_set_mem_attr(struct kvm *kvm, int attr, gfn_t start, gfn_t end);
> >   void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot,
> >   			      unsigned int attr, gfn_t start, gfn_t end);
> >   #else
> > +static inline int kvm_vm_reserve_mem_attr(struct kvm *kvm, gfn_t start, gfn_t end)
> > +{
> > +	return -EOPNOTSUPP;
> > +}
> > +static inline int kvm_vm_set_mem_attr(struct kvm *kvm, int attr, gfn_t start, gfn_t end)
> > +{
> > +	return -EOPNOTSUPP;
> > +}
> >   static inline void kvm_arch_update_mem_attr(struct kvm *kvm,
> >   					    struct kvm_memory_slot *slot,
> >   					    unsigned int attr,
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index 9f82b03a8118..f0e77b65939b 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -1121,6 +1121,80 @@ static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot)
> >   					  &slot->notifier);
> >   }
> > +/*
> > + * Reserve memory for [start, end) so that the next set oepration won't fail
> > + * with -ENOMEM.
> > + */
> > +int kvm_vm_reserve_mem_attr(struct kvm *kvm, gfn_t start, gfn_t end)
> > +{
> > +	int r = 0;
> > +	gfn_t gfn;
> > +
> > +	xa_lock(&kvm->mem_attr_array);
> > +	for (gfn = start; gfn < end; gfn++) {
> > +		r = __xa_insert(&kvm->mem_attr_array, gfn, NULL, GFP_KERNEL_ACCOUNT);
> > +		if (r == -EBUSY)
> > +			r = 0;
> > +		if (r)
> > +			break;
> > +	}
> > +	xa_unlock(&kvm->mem_attr_array);
> > +
> > +	return r;
> > +}
> > +EXPORT_SYMBOL_GPL(kvm_vm_reserve_mem_attr);
> > +
> > +/* Set memory attr for [start, end) */
> > +int kvm_vm_set_mem_attr(struct kvm *kvm, int attr, gfn_t start, gfn_t end)
> > +{
> > +	void *entry;
> > +	gfn_t gfn;
> > +	int r;
> > +	int i;
> > +
> > +	/* By default, the entry is private. */
> > +	switch (attr) {
> > +	case KVM_MEM_ATTR_PRIVATE:
> > +		entry = NULL;
> > +		break;
> > +	case KVM_MEM_ATTR_SHARED:
> > +		entry = xa_mk_value(KVM_MEM_ATTR_SHARED);
> > +		break;
> > +	default:
> > +		WARN_ON_ONCE(1);
> > +		return -EINVAL;
> > +	}
> > +
> > +	WARN_ON_ONCE(start >= end);
> > +	for (gfn = start; gfn < end; gfn++) {
> > +		r = xa_err(xa_store(&kvm->mem_attr_array, gfn, entry,
> > +				    GFP_KERNEL_ACCOUNT));
> > +		if (r)
> > +			break;
> > +	}
> > +	if (start >= gfn)
> > +		return r;
> > +
> > +	end = gfn;
> > +	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
> > +		struct kvm_memslot_iter iter;
> > +		struct kvm_memory_slot *slot;
> > +		struct kvm_memslots *slots;
> > +
> > +		slots = __kvm_memslots(kvm, i);
> > +		kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) {
> 
> slot needs to be set as
> 
> 			slot = iter.slot;
> 

Thanks, will fix it.

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