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dkim-atps=neutral Received: by ozlabs.org (Postfix, from userid 1007) id 448v5k6xKzz9s47; Thu, 28 Feb 2019 11:47:22 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1551314842; bh=7F9jVzrmCExevuR1705D7iejU3i6DDP1p9rKk51nz4w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mv7XWyrbe33dcZzqNNwVU99aT1A/szBKT65de0S1MOP+KlvjBaz0cWOp5AblYFY2X 97TGHZxq+qWZomfB4TaafRfJPPiUqbvaxLqRB8XBFkwneKX96nhN98rk1+DEQKBMbb iVojbLiYSZJkTuja/syLwS08n/EwrJ+WEb/OyuIo= Date: Thu, 28 Feb 2019 11:15:46 +1100 From: David Gibson To: Alexey Kardashevskiy Subject: Re: [PATCH kernel] KVM: PPC: Allocate guest TCEs on demand too Message-ID: <20190228001546.GA7734@umbus.fritz.box> References: <20190227084235.22795-1-aik@ozlabs.ru> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0F1p//8PRICkK4MW" Content-Disposition: inline In-Reply-To: <20190227084235.22795-1-aik@ozlabs.ru> User-Agent: Mutt/1.11.3 (2019-02-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" --0F1p//8PRICkK4MW Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 27, 2019 at 07:42:35PM +1100, Alexey Kardashevskiy wrote: > We already allocate hardware TCE tables in multiple levels and skip > intermediate levels when we can, now it is a turn of the KVM TCE tables. > Thankfully these are allocated already in 2 levels. >=20 > This moves the table's last level allocation from the creating helper to > kvmppc_tce_put() and kvm_spapr_tce_fault(). >=20 > This adds kvmppc_rm_ioba_validate() to do an additional test if > the consequent kvmppc_tce_put() needs a page which has not been allocated; > if this is the case, we bail out to virtual mode handlers. >=20 > Signed-off-by: Alexey Kardashevskiy Reviewed-by: David Gibson > --- >=20 > For NVLink2 passthrough guests with 128TiB DMA windows (when we push GPU = RAM > above the PCI MMIO window in the guest) and very fragmented system RAM > the difference is about 16GiB of RAM before and after this patch. >=20 > --- > arch/powerpc/kvm/book3s_64_vio.c | 21 ++++------ > arch/powerpc/kvm/book3s_64_vio_hv.c | 62 ++++++++++++++++++++++++++--- > 2 files changed, 64 insertions(+), 19 deletions(-) >=20 > diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_6= 4_vio.c > index f02b049..281b56b 100644 > --- a/arch/powerpc/kvm/book3s_64_vio.c > +++ b/arch/powerpc/kvm/book3s_64_vio.c > @@ -228,7 +228,8 @@ static void release_spapr_tce_table(struct rcu_head *= head) > unsigned long i, npages =3D kvmppc_tce_pages(stt->size); > =20 > for (i =3D 0; i < npages; i++) > - __free_page(stt->pages[i]); > + if (stt->pages[i]) > + __free_page(stt->pages[i]); > =20 > kfree(stt); > } > @@ -241,6 +242,12 @@ static vm_fault_t kvm_spapr_tce_fault(struct vm_faul= t *vmf) > if (vmf->pgoff >=3D kvmppc_tce_pages(stt->size)) > return VM_FAULT_SIGBUS; > =20 > + if (!stt->pages[vmf->pgoff]) { > + stt->pages[vmf->pgoff] =3D alloc_page(GFP_KERNEL | __GFP_ZERO); > + if (!stt->pages[vmf->pgoff]) > + return VM_FAULT_OOM; > + } > + > page =3D stt->pages[vmf->pgoff]; > get_page(page); > vmf->page =3D page; > @@ -296,7 +303,6 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, > struct kvmppc_spapr_tce_table *siter; > unsigned long npages, size =3D args->size; > int ret =3D -ENOMEM; > - int i; > =20 > if (!args->size || args->page_shift < 12 || args->page_shift > 34 || > (args->offset + args->size > (ULLONG_MAX >> args->page_shift))) > @@ -320,12 +326,6 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, > stt->kvm =3D kvm; > INIT_LIST_HEAD_RCU(&stt->iommu_tables); > =20 > - for (i =3D 0; i < npages; i++) { > - stt->pages[i] =3D alloc_page(GFP_KERNEL | __GFP_ZERO); > - if (!stt->pages[i]) > - goto fail; > - } > - > mutex_lock(&kvm->lock); > =20 > /* Check this LIOBN hasn't been previously allocated */ > @@ -352,11 +352,6 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, > if (ret >=3D 0) > return ret; > =20 > - fail: > - for (i =3D 0; i < npages; i++) > - if (stt->pages[i]) > - __free_page(stt->pages[i]); > - > kfree(stt); > fail_acct: > kvmppc_account_memlimit(kvmppc_stt_pages(npages), false); > diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3= s_64_vio_hv.c > index 2206bc7..fbb920d 100644 > --- a/arch/powerpc/kvm/book3s_64_vio_hv.c > +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c > @@ -158,23 +158,69 @@ static u64 *kvmppc_page_address(struct page *page) > return (u64 *) page_address(page); > } > =20 > +/* > + * TCEs pages are allocated in kvmppc_tce_put() which won't be able to d= o so > + * in real mode. > + * Check if kvmppc_tce_put() can succeed in real mode, i.e. a TCEs page = is > + * allocated or not required (when clearing a tce entry). > + */ > +static long kvmppc_rm_ioba_validate(struct kvmppc_spapr_tce_table *stt, > + unsigned long ioba, unsigned long npages, bool clearing) > +{ > + unsigned long i, sttpage, sttpages; > + unsigned long ret =3D kvmppc_ioba_validate(stt, ioba, npages); > + > + if (ret) > + return ret; > + /* > + * clearing=3D=3Dtrue says kvmppc_tce_put won't be allocating pages > + * for empty tces. > + */ > + if (clearing) > + return H_SUCCESS; > + > + sttpage =3D ((ioba >> stt->page_shift) - stt->offset) / TCES_PER_PAGE; > + sttpages =3D (npages + TCES_PER_PAGE - 1) / TCES_PER_PAGE; > + for (i =3D sttpage; i < sttpage + sttpages; ++i) > + if (!stt->pages[i]) > + return H_TOO_HARD; > + > + return H_SUCCESS; > +} > + > /* > * Handles TCE requests for emulated devices. > * Puts guest TCE values to the table and expects user space to convert = them. > * Called in both real and virtual modes. > * Cannot fail so kvmppc_tce_validate must be called before it. > * > - * WARNING: This will be called in real-mode on HV KVM and virtual > - * mode on PR KVM > + * WARNING: This will be called in real-mode on HV HPT KVM and virtual > + * mode on PR KVM or HV radix KVM > */ > void kvmppc_tce_put(struct kvmppc_spapr_tce_table *stt, > unsigned long idx, unsigned long tce) > { > struct page *page; > u64 *tbl; > + unsigned long sttpage; > =20 > idx -=3D stt->offset; > - page =3D stt->pages[idx / TCES_PER_PAGE]; > + sttpage =3D idx / TCES_PER_PAGE; > + page =3D stt->pages[sttpage]; > + > + if (!page) { > + /* We allow any TCE, not just with read|write permissions */ > + if (!tce) > + return; > + /* > + * We must not end up here in real mode, > + * kvmppc_rm_ioba_validate() takes care of this. > + */ > + page =3D alloc_page(GFP_KERNEL | __GFP_ZERO); > + if (WARN_ON_ONCE(!page)) > + return; > + stt->pages[sttpage] =3D page; > + } > tbl =3D kvmppc_page_address(page); > =20 > tbl[idx % TCES_PER_PAGE] =3D tce; > @@ -381,7 +427,7 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsig= ned long liobn, > if (!stt) > return H_TOO_HARD; > =20 > - ret =3D kvmppc_ioba_validate(stt, ioba, 1); > + ret =3D kvmppc_rm_ioba_validate(stt, ioba, 1, tce =3D=3D 0); > if (ret !=3D H_SUCCESS) > return ret; > =20 > @@ -480,7 +526,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vc= pu, > if (tce_list & (SZ_4K - 1)) > return H_PARAMETER; > =20 > - ret =3D kvmppc_ioba_validate(stt, ioba, npages); > + ret =3D kvmppc_rm_ioba_validate(stt, ioba, npages, false); > if (ret !=3D H_SUCCESS) > return ret; > =20 > @@ -583,7 +629,7 @@ long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu, > if (!stt) > return H_TOO_HARD; > =20 > - ret =3D kvmppc_ioba_validate(stt, ioba, npages); > + ret =3D kvmppc_rm_ioba_validate(stt, ioba, npages, tce_value =3D=3D 0); > if (ret !=3D H_SUCCESS) > return ret; > =20 > @@ -635,6 +681,10 @@ long kvmppc_h_get_tce(struct kvm_vcpu *vcpu, unsigne= d long liobn, > =20 > idx =3D (ioba >> stt->page_shift) - stt->offset; > page =3D stt->pages[idx / TCES_PER_PAGE]; > + if (!page) { > + vcpu->arch.regs.gpr[4] =3D 0; > + return H_SUCCESS; > + } > tbl =3D (u64 *)page_address(page); > =20 > vcpu->arch.regs.gpr[4] =3D tbl[idx % TCES_PER_PAGE]; --=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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