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Fri, 25 Jul 2025 07:41:05 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20250714221545.5615-1-romank@linux.microsoft.com> <20250714221545.5615-13-romank@linux.microsoft.com> In-Reply-To: <20250714221545.5615-13-romank@linux.microsoft.com> From: Tianyu Lan Date: Fri, 25 Jul 2025 22:40:29 +0800 X-Gm-Features: Ac12FXxEB_FL3_rT6cHSVkdJsOhCBETxNq543NIYn_bXKIfHCNGG5wd0r0RZbmw Message-ID: Subject: Re: [PATCH hyperv-next v4 12/16] Drivers: hv: Allocate encrypted buffers when requested To: Roman Kisel Cc: alok.a.tiwari@oracle.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, dave.hansen@linux.intel.com, decui@microsoft.com, haiyangz@microsoft.com, hpa@zytor.com, kys@microsoft.com, mhklinux@outlook.com, mingo@redhat.com, rdunlap@infradead.org, tglx@linutronix.de, Tianyu.Lan@microsoft.com, wei.liu@kernel.org, linux-arch@vger.kernel.org, linux-coco@lists.linux.dev, linux-doc@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, apais@microsoft.com, benhill@microsoft.com, bperkins@microsoft.com, sunilmut@microsoft.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Jul 15, 2025 at 6:28=E2=80=AFAM Roman Kisel wrote: > > Confidential VMBus is built around using buffers not shared with > the host. > > Support allocating encrypted buffers when requested. > > Signed-off-by: Roman Kisel > --- Reviewed-by: Tianyu Lan > drivers/hv/channel.c | 49 +++++++++++++++++++++++---------------- > drivers/hv/hyperv_vmbus.h | 3 ++- > drivers/hv/ring_buffer.c | 5 ++-- > 3 files changed, 34 insertions(+), 23 deletions(-) > > diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c > index 35f26fa1ffe7..051eeba800f2 100644 > --- a/drivers/hv/channel.c > +++ b/drivers/hv/channel.c > @@ -443,20 +443,23 @@ static int __vmbus_establish_gpadl(struct vmbus_cha= nnel *channel, > return ret; > } > > - /* > - * Set the "decrypted" flag to true for the set_memory_decrypted(= ) > - * success case. In the failure case, the encryption state of the > - * memory is unknown. Leave "decrypted" as true to ensure the > - * memory will be leaked instead of going back on the free list. > - */ > - gpadl->decrypted =3D true; > - ret =3D set_memory_decrypted((unsigned long)kbuffer, > - PFN_UP(size)); > - if (ret) { > - dev_warn(&channel->device_obj->device, > - "Failed to set host visibility for new GPADL %d.= \n", > - ret); > - return ret; > + gpadl->decrypted =3D !((channel->co_external_memory && type =3D= =3D HV_GPADL_BUFFER) || > + (channel->co_ring_buffer && type =3D=3D HV_GPADL_RING)); > + if (gpadl->decrypted) { > + /* > + * The "decrypted" flag being true assumes that set_memor= y_decrypted() succeeds. > + * But if it fails, the encryption state of the memory is= unknown. In that case, > + * leave "decrypted" as true to ensure the memory is leak= ed instead of going back > + * on the free list. > + */ > + ret =3D set_memory_decrypted((unsigned long)kbuffer, > + PFN_UP(size)); > + if (ret) { > + dev_warn(&channel->device_obj->device, > + "Failed to set host visibility for new GP= ADL %d.\n", > + ret); > + return ret; > + } > } > > init_completion(&msginfo->waitevent); > @@ -544,8 +547,10 @@ static int __vmbus_establish_gpadl(struct vmbus_chan= nel *channel, > * left as true so the memory is leaked instead of being > * put back on the free list. > */ > - if (!set_memory_encrypted((unsigned long)kbuffer, PFN_UP(= size))) > - gpadl->decrypted =3D false; > + if (gpadl->decrypted) { > + if (!set_memory_encrypted((unsigned long)kbuffer,= PFN_UP(size))) > + gpadl->decrypted =3D false; > + } > } > > return ret; > @@ -676,12 +681,13 @@ static int __vmbus_open(struct vmbus_channel *newch= annel, > goto error_clean_ring; > > err =3D hv_ringbuffer_init(&newchannel->outbound, > - page, send_pages, 0); > + page, send_pages, 0, newchannel->co_ring= _buffer); > if (err) > goto error_free_gpadl; > > err =3D hv_ringbuffer_init(&newchannel->inbound, &page[send_pages= ], > - recv_pages, newchannel->max_pkt_size); > + recv_pages, newchannel->max_pkt_size, > + newchannel->co_ring_buffer); > if (err) > goto error_free_gpadl; > > @@ -862,8 +868,11 @@ int vmbus_teardown_gpadl(struct vmbus_channel *chann= el, struct vmbus_gpadl *gpad > > kfree(info); > > - ret =3D set_memory_encrypted((unsigned long)gpadl->buffer, > - PFN_UP(gpadl->size)); > + if (gpadl->decrypted) > + ret =3D set_memory_encrypted((unsigned long)gpadl->buffer= , > + PFN_UP(gpadl->size)); > + else > + ret =3D 0; > if (ret) > pr_warn("Fail to set mem host visibility in GPADL teardow= n %d.\n", ret); > > diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h > index 2873703d08a9..beae68a70939 100644 > --- a/drivers/hv/hyperv_vmbus.h > +++ b/drivers/hv/hyperv_vmbus.h > @@ -200,7 +200,8 @@ extern int hv_synic_cleanup(unsigned int cpu); > void hv_ringbuffer_pre_init(struct vmbus_channel *channel); > > int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, > - struct page *pages, u32 pagecnt, u32 max_pkt_size)= ; > + struct page *pages, u32 pagecnt, u32 max_pkt_size, > + bool confidential); > > void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info); > > diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c > index 3c9b02471760..05c2cd42fc75 100644 > --- a/drivers/hv/ring_buffer.c > +++ b/drivers/hv/ring_buffer.c > @@ -183,7 +183,8 @@ void hv_ringbuffer_pre_init(struct vmbus_channel *cha= nnel) > > /* Initialize the ring buffer. */ > int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, > - struct page *pages, u32 page_cnt, u32 max_pkt_size= ) > + struct page *pages, u32 page_cnt, u32 max_pkt_size= , > + bool confidential) > { > struct page **pages_wraparound; > int i; > @@ -207,7 +208,7 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ri= ng_info, > > ring_info->ring_buffer =3D (struct hv_ring_buffer *) > vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP, > - pgprot_decrypted(PAGE_KERNEL)); > + confidential ? PAGE_KERNEL : pgprot_decrypted(PAG= E_KERNEL)); > > kfree(pages_wraparound); > if (!ring_info->ring_buffer) > -- > 2.43.0 > > --=20 Thanks Tianyu Lan