From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3vsX576BpQzDqC2 for ; Tue, 28 Mar 2017 11:36:27 +1100 (AEDT) Date: Tue, 28 Mar 2017 11:14:06 +1100 From: David Gibson To: Alexey Kardashevskiy Cc: linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, Paul Mackerras Subject: Re: [PATCH kernel] KVM: PPC: Preserve storage control bits Message-ID: <20170328001406.GB13461@umbus.fritz.box> References: <20170324064922.18429-1-aik@ozlabs.ru> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="9zSXsLTf0vkW971A" In-Reply-To: <20170324064922.18429-1-aik@ozlabs.ru> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --9zSXsLTf0vkW971A Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Mar 24, 2017 at 05:49:22PM +1100, Alexey Kardashevskiy wrote: > PR KVM page fault handler performs eaddr to pte translation for a guest, > however kvmppc_mmu_book3s_64_xlate() does not preserve WIMG bits > (storage control) in the kvmppc_pte struct. If PR KVM is running as > a second level guest under HV KVM, and PR KVM tries inserting HPT entry, > this fails in HV KVM if it already has this mapping. >=20 > This preserves WIMG bits between kvmppc_mmu_book3s_64_xlate() and > kvmppc_mmu_map_page(). >=20 > Signed-off-by: Alexey Kardashevskiy Reviewed-by: David Gibson > --- >=20 > This allows MMIO BAR mapping for nested guest with VFIO. >=20 > This is the check in HV KVM which failed: >=20 > arch/powerpc/kvm/book3s_hv_rm_mmu.c > long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, > [...] >=20 > /*If we had host pte mapping then Check WIMG */ > if (ptep && !hpte_cache_flags_ok(ptel, is_ci)) { > if (is_ci) > return H_PARAMETER; > /* > * Allow guest to map emulated device memory as > * uncacheable, but actually make it cacheable. > */ > ptel &=3D ~(HPTE_R_W|HPTE_R_I|HPTE_R_G); > ptel |=3D HPTE_R_M; > } > --- > arch/powerpc/include/asm/kvm_host.h | 1 + > arch/powerpc/kvm/book3s_64_mmu.c | 1 + > arch/powerpc/kvm/book3s_64_mmu_host.c | 2 ++ > arch/powerpc/kvm/book3s_pr.c | 2 +- > 4 files changed, 5 insertions(+), 1 deletion(-) >=20 > diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/a= sm/kvm_host.h > index 7bba8f415627..bf6822cd4f86 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -345,6 +345,7 @@ struct kvmppc_pte { > bool may_read : 1; > bool may_write : 1; > bool may_execute : 1; > + unsigned long wimg; > u8 page_size; /* MMU_PAGE_xxx */ > }; > =20 > diff --git a/arch/powerpc/kvm/book3s_64_mmu.c b/arch/powerpc/kvm/book3s_6= 4_mmu.c > index 70153578131a..29ebe2fd5867 100644 > --- a/arch/powerpc/kvm/book3s_64_mmu.c > +++ b/arch/powerpc/kvm/book3s_64_mmu.c > @@ -319,6 +319,7 @@ static int kvmppc_mmu_book3s_64_xlate(struct kvm_vcpu= *vcpu, gva_t eaddr, > gpte->may_execute =3D true; > gpte->may_read =3D false; > gpte->may_write =3D false; > + gpte->wimg =3D r & HPTE_R_WIMG; > =20 > switch (pp) { > case 0: > diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/boo= k3s_64_mmu_host.c > index 4b4e927c4822..145a61892c48 100644 > --- a/arch/powerpc/kvm/book3s_64_mmu_host.c > +++ b/arch/powerpc/kvm/book3s_64_mmu_host.c > @@ -145,6 +145,8 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct= kvmppc_pte *orig_pte, > else > kvmppc_mmu_flush_icache(pfn); > =20 > + rflags =3D (rflags & ~HPTE_R_WIMG) | orig_pte->wimg; > + > /* > * Use 64K pages if possible; otherwise, on 64K page kernels, > * we need to transfer 4 more bits from guest real to host real addr. > diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c > index ce437b98477e..f026b062c0ed 100644 > --- a/arch/powerpc/kvm/book3s_pr.c > +++ b/arch/powerpc/kvm/book3s_pr.c > @@ -537,7 +537,7 @@ int kvmppc_handle_pagefault(struct kvm_run *run, stru= ct kvm_vcpu *vcpu, > int r =3D RESUME_GUEST; > int relocated; > int page_found =3D 0; > - struct kvmppc_pte pte; > + struct kvmppc_pte pte =3D { 0 }; > bool dr =3D (kvmppc_get_msr(vcpu) & MSR_DR) ? true : false; > bool ir =3D (kvmppc_get_msr(vcpu) & MSR_IR) ? true : false; > u64 vsid; --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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