From: janani <janani@linux.ibm.com>
To: Bharata B Rao <bharata@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, linuxram@us.ibm.com,
cclaudio@linux.ibm.com, kvm-ppc@vger.kernel.org,
linux-mm@kvack.org, jglisse@redhat.com,
aneesh.kumar@linux.vnet.ibm.com, paulus@au1.ibm.com,
sukadev@linux.vnet.ibm.com,
Linuxppc-dev
<linuxppc-dev-bounces+janani=linux.ibm.com@lists.ozlabs.org>
Subject: Re: [PATCH v5 2/7] kvmppc: Shared pages support for secure guests
Date: Tue, 09 Jul 2019 14:35:02 -0500 [thread overview]
Message-ID: <e73fbe2bb6617da8245c1164aa7c8b57@linux.vnet.ibm.com> (raw)
In-Reply-To: <20190709102545.9187-3-bharata@linux.ibm.com>
On 2019-07-09 05:25, Bharata B Rao wrote:
> A secure guest will share some of its pages with hypervisor (Eg. virtio
> bounce buffers etc). Support shared pages in HMM driver.
>
> Once a secure page is converted to shared page, HMM driver will stop
> tracking that page.
>
> Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
Reviewed-by: Janani Janakiraman <janani@linux.ibm.com>
> ---
> arch/powerpc/include/asm/hvcall.h | 3 ++
> arch/powerpc/kvm/book3s_hv_hmm.c | 66 +++++++++++++++++++++++++++++--
> 2 files changed, 66 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/hvcall.h
> b/arch/powerpc/include/asm/hvcall.h
> index 2f6b952deb0f..05b8536f6653 100644
> --- a/arch/powerpc/include/asm/hvcall.h
> +++ b/arch/powerpc/include/asm/hvcall.h
> @@ -337,6 +337,9 @@
> #define H_TLB_INVALIDATE 0xF808
> #define H_COPY_TOFROM_GUEST 0xF80C
>
> +/* Flags for H_SVM_PAGE_IN */
> +#define H_PAGE_IN_SHARED 0x1
> +
> /* Platform-specific hcalls used by the Ultravisor */
> #define H_SVM_PAGE_IN 0xEF00
> #define H_SVM_PAGE_OUT 0xEF04
> diff --git a/arch/powerpc/kvm/book3s_hv_hmm.c
> b/arch/powerpc/kvm/book3s_hv_hmm.c
> index cd34323888b6..36562b382e70 100644
> --- a/arch/powerpc/kvm/book3s_hv_hmm.c
> +++ b/arch/powerpc/kvm/book3s_hv_hmm.c
> @@ -52,6 +52,7 @@ struct kvmppc_hmm_page_pvt {
> unsigned long *rmap;
> unsigned int lpid;
> unsigned long gpa;
> + bool skip_page_out;
> };
>
> struct kvmppc_hmm_migrate_args {
> @@ -215,6 +216,53 @@ static const struct migrate_vma_ops
> kvmppc_hmm_migrate_ops = {
> .finalize_and_map = kvmppc_hmm_migrate_finalize_and_map,
> };
>
> +/*
> + * Shares the page with HV, thus making it a normal page.
> + *
> + * - If the page is already secure, then provision a new page and
> share
> + * - If the page is a normal page, share the existing page
> + *
> + * In the former case, uses the HMM fault handler to release the HMM
> page.
> + */
> +static unsigned long
> +kvmppc_share_page(struct kvm *kvm, unsigned long gpa, unsigned long
> page_shift)
> +{
> +
> + int ret;
> + struct page *hmm_page;
> + struct kvmppc_hmm_page_pvt *pvt;
> + unsigned long pfn;
> + unsigned long *rmap;
> + struct kvm_memory_slot *slot;
> + unsigned long gfn = gpa >> page_shift;
> + int srcu_idx;
> +
> + srcu_idx = srcu_read_lock(&kvm->srcu);
> + slot = gfn_to_memslot(kvm, gfn);
> + if (!slot) {
> + srcu_read_unlock(&kvm->srcu, srcu_idx);
> + return H_PARAMETER;
> + }
> + rmap = &slot->arch.rmap[gfn - slot->base_gfn];
> + srcu_read_unlock(&kvm->srcu, srcu_idx);
> +
> + if (kvmppc_is_hmm_pfn(*rmap)) {
> + hmm_page = pfn_to_page(*rmap & ~KVMPPC_PFN_HMM);
> + pvt = (struct kvmppc_hmm_page_pvt *)
> + hmm_devmem_page_get_drvdata(hmm_page);
> + pvt->skip_page_out = true;
> + }
> +
> + pfn = gfn_to_pfn(kvm, gpa >> page_shift);
> + if (is_error_noslot_pfn(pfn))
> + return H_PARAMETER;
> +
> + ret = uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0,
> page_shift);
> + kvm_release_pfn_clean(pfn);
> +
> + return (ret == U_SUCCESS) ? H_SUCCESS : H_PARAMETER;
> +}
> +
> /*
> * Move page from normal memory to secure memory.
> */
> @@ -235,9 +283,12 @@ kvmppc_h_svm_page_in(struct kvm *kvm, unsigned
> long gpa,
> if (page_shift != PAGE_SHIFT)
> return H_P3;
>
> - if (flags)
> + if (flags & ~H_PAGE_IN_SHARED)
> return H_P2;
>
> + if (flags & H_PAGE_IN_SHARED)
> + return kvmppc_share_page(kvm, gpa, page_shift);
> +
> down_read(&kvm->mm->mmap_sem);
> srcu_idx = srcu_read_lock(&kvm->srcu);
> slot = gfn_to_memslot(kvm, gfn);
> @@ -299,8 +350,17 @@ kvmppc_hmm_fault_migrate_alloc_and_copy(struct
> vm_area_struct *vma,
> hmm_devmem_page_get_drvdata(spage);
>
> pfn = page_to_pfn(dpage);
> - ret = uv_page_out(pvt->lpid, pfn << PAGE_SHIFT,
> - pvt->gpa, 0, PAGE_SHIFT);
> +
> + /*
> + * This same alloc_and_copy() callback is used in two cases:
> + * - When HV touches a secure page, for which we do page-out
> + * - When a secure page is converted to shared page, we touch
> + * the page to essentially discard the HMM page. In this case we
> + * skip page-out.
> + */
> + if (!pvt->skip_page_out)
> + ret = uv_page_out(pvt->lpid, pfn << PAGE_SHIFT,
> + pvt->gpa, 0, PAGE_SHIFT);
> if (ret == U_SUCCESS)
> *dst_pfn = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED;
> }
next prev parent reply other threads:[~2019-07-09 19:32 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-09 10:25 [PATCH v5 0/7] kvmppc: HMM driver to manage pages of secure guest Bharata B Rao
2019-07-09 10:25 ` [PATCH v5 1/7] kvmppc: HMM backend " Bharata B Rao
2019-07-09 18:55 ` janani
2019-07-10 13:47 ` Jason Gunthorpe
2019-07-11 5:08 ` Bharata B Rao
2019-07-19 6:46 ` Christoph Hellwig
2019-07-19 8:14 ` Bharata B Rao
2019-07-09 10:25 ` [PATCH v5 2/7] kvmppc: Shared pages support for secure guests Bharata B Rao
2019-07-09 19:35 ` janani [this message]
2019-07-09 10:25 ` [PATCH v5 3/7] kvmppc: H_SVM_INIT_START and H_SVM_INIT_DONE hcalls Bharata B Rao
2019-07-09 19:42 ` janani
2019-07-09 10:25 ` [PATCH v5 4/7] kvmppc: Handle memory plug/unplug to secure VM Bharata B Rao
2019-07-09 19:43 ` janani
2019-07-09 10:25 ` [RFC PATCH v5 5/7] kvmppc: Radix changes for secure guest Bharata B Rao
2019-07-09 19:53 ` janani
2019-07-09 10:25 ` [RFC PATCH v5 6/7] kvmppc: Support reset of " Bharata B Rao
2019-07-10 13:30 ` janani
2019-07-09 10:25 ` [PATCH v5 7/7] KVM: PPC: Ultravisor: Add PPC_UV config option Bharata B Rao
2019-07-10 13:24 ` janani
2019-07-10 14:15 ` Jason Gunthorpe
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