Re: [PATCH 2/2] KVM: arm64: Don't map 'kvm_vgic_global_state' at EL2 with pKVM

[Marc Zyngier <maz@kernel.org>]

On Wed, 23 Oct 2024 17:39:08 +0100,
Will Deacon <will@kernel.org> wrote:
> 
> On Tue, Oct 22, 2024 at 06:01:17PM +0100, Marc Zyngier wrote:
> > On Tue, 22 Oct 2024 15:40:16 +0100,
> > Will Deacon <will@kernel.org> wrote:
> > > 
> > > Now that 'kvm_vgic_global_state' is no longer needed for ICC_CTLR_EL1
> > > emulation on machines with a broken SEIS implementation, drop the
> > > pKVM hypervisor mapping of the page.
> > > 
> > > Cc: Marc Zyngier <maz@kernel.org>
> > > Cc: Oliver Upton <oliver.upton@linux.dev>
> > > Signed-off-by: Will Deacon <will@kernel.org>
> > > ---
> > >  arch/arm64/kvm/hyp/nvhe/setup.c | 17 -----------------
> > >  1 file changed, 17 deletions(-)
> > > 
> > > diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
> > > index 174007f3fadd..8fec099c2775 100644
> > > --- a/arch/arm64/kvm/hyp/nvhe/setup.c
> > > +++ b/arch/arm64/kvm/hyp/nvhe/setup.c
> > > @@ -95,7 +95,6 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
> > >  {
> > >  	void *start, *end, *virt = hyp_phys_to_virt(phys);
> > >  	unsigned long pgt_size = hyp_s1_pgtable_pages() << PAGE_SHIFT;
> > > -	enum kvm_pgtable_prot prot;
> > >  	int ret, i;
> > >  
> > >  	/* Recreate the hyp page-table using the early page allocator */
> > > @@ -148,22 +147,6 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
> > >  	}
> > >  
> > >  	pkvm_create_host_sve_mappings();
> > > -
> > > -	/*
> > > -	 * Map the host sections RO in the hypervisor, but transfer the
> > > -	 * ownership from the host to the hypervisor itself to make sure they
> > > -	 * can't be donated or shared with another entity.
> > > -	 *
> > > -	 * The ownership transition requires matching changes in the host
> > > -	 * stage-2. This will be done later (see finalize_host_mappings()) once
> > > -	 * the hyp_vmemmap is addressable.
> > > -	 */
> > > -	prot = pkvm_mkstate(PAGE_HYP_RO, PKVM_PAGE_SHARED_OWNED);
> > > -	ret = pkvm_create_mappings(&kvm_vgic_global_state,
> > > -				   &kvm_vgic_global_state + 1, prot);
> > > -	if (ret)
> > > -		return ret;
> > > -
> > >  	return 0;
> > >  }
> > 
> > Maybe add a note indicating that nVHE/hVHE still have that particular
> > mapping via the rodata section?
> 
> I can add something to the commit message, is that what you had in mind?

Yes. But maybe Oliver can add that when applying the series?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.