Re: [PATCH 12/20] KVM: arm64: Handle huge mappings in __pkvm_host_force_reclaim_page_guest()

[Vincent Donnefort <vdonnefort@google.com>]

On Mon, Sep 07, 2026 at 05:52:35PM +0100, Wei-Lin Chang wrote:
> On Mon, Aug 03, 2026 at 11:08:56AM +0100, Vincent Donnefort wrote:
> 
> [...]
> 
> > -static void hyp_poison_page(phys_addr_t phys)
> > +static void __hyp_poison_page(void *addr, size_t size)
> >  {
> > -	void *addr = hyp_fixmap_map(phys);
> > -
> > -	memset(addr, 0, PAGE_SIZE);
> > +	memset(addr, 0, size);
> >  	/*
> >  	 * Prefer kvm_flush_dcache_to_poc() over __clean_dcache_guest_page()
> >  	 * here as the latter may elide the CMO under the assumption that FWB
> > @@ -1304,19 +1302,15 @@ static void hyp_poison_page(phys_addr_t phys)
> >  	 * host stage-2 and would otherwise lead to a malicious host potentially
> >  	 * being able to read the contents of newly reclaimed guest pages.
> >  	 */
> > -	kvm_flush_dcache_to_poc(addr, PAGE_SIZE);
> > -	hyp_fixmap_unmap();
> > +	kvm_flush_dcache_to_poc(addr, size);
> >  }
> >  
> >  static void hyp_poison_range(phys_addr_t phys, u64 size)
> >  {
> > -	u64 offset;
> > -
> > -	for (offset = 0; offset < size; offset += PAGE_SIZE)
> > -		hyp_poison_page(phys + offset);
> > +	__apply_guest_page(__hyp_va(phys), size, __hyp_poison_page);
> >  }
> 
> Patch 8 introduces hyp_poison_range(), and it is reimplemented in
> another way here. Maybe just do it this way in the first time?

Especially if I split it into a separate patch.

> 
> >  
> > -static int host_stage2_get_guest_info(phys_addr_t phys, struct pkvm_hyp_vm **vm,
> > +static int host_stage2_get_guest_info(phys_addr_t phys, u64 *size, struct pkvm_hyp_vm **vm,
> >  				      u64 *gfn)
> >  {
> >  	enum pkvm_page_state state;
> > @@ -1344,34 +1338,43 @@ static int host_stage2_get_guest_info(phys_addr_t phys, struct pkvm_hyp_vm **vm,
> >  	if (ret)
> >  		return ret;
> >  
> > -	if (WARN_ON(level != KVM_PGTABLE_LAST_LEVEL))
> > -		return -EINVAL;
> > +	/* We only support either PAGE_SIZE or PMD_SIZE */
> > +	if (level < KVM_PGTABLE_LAST_LEVEL - 1)
> > +		return -E2BIG;
> >  
> > -	return host_stage2_decode_gfn_meta(pte, vm, gfn);
> > +	ret = host_stage2_decode_gfn_meta(pte, vm, gfn);
> > +	if (ret)
> > +		return ret;
> > +
> > +	*size = kvm_granule_size(level);
> > +
> > +	return 0;
> 
> This can also be moved into its own patch with get_valid_guest_pte(),
> hyp_poison_range() changes in my opinion.
> 
> Thanks,
> Wei-Lin Chang
> 
> [...]