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Message-ID: <MWHPR21MB15933BC87034940AB7170552D7AC9@MWHPR21MB1593.namprd21.prod.outlook.com>
Date: Sat, 2 Oct 2021 13:26:26 +0000
From: Michael Kelley <mikelley@...rosoft.com>
To: Tianyu Lan <ltykernel@...il.com>,
KY Srinivasan <kys@...rosoft.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Stephen Hemminger <sthemmin@...rosoft.com>,
"wei.liu@...nel.org" <wei.liu@...nel.org>,
Dexuan Cui <decui@...rosoft.com>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"mingo@...hat.com" <mingo@...hat.com>,
"bp@...en8.de" <bp@...en8.de>, "x86@...nel.org" <x86@...nel.org>,
"hpa@...or.com" <hpa@...or.com>,
"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
"luto@...nel.org" <luto@...nel.org>,
"peterz@...radead.org" <peterz@...radead.org>,
"davem@...emloft.net" <davem@...emloft.net>,
"kuba@...nel.org" <kuba@...nel.org>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"arnd@...db.de" <arnd@...db.de>,
"brijesh.singh@....com" <brijesh.singh@....com>,
"jroedel@...e.de" <jroedel@...e.de>,
Tianyu Lan <Tianyu.Lan@...rosoft.com>,
"thomas.lendacky@....com" <thomas.lendacky@....com>,
"pgonda@...gle.com" <pgonda@...gle.com>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"rppt@...nel.org" <rppt@...nel.org>,
"kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
"saravanand@...com" <saravanand@...com>,
"aneesh.kumar@...ux.ibm.com" <aneesh.kumar@...ux.ibm.com>,
"rientjes@...gle.com" <rientjes@...gle.com>,
"tj@...nel.org" <tj@...nel.org>
CC: "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
vkuznets <vkuznets@...hat.com>,
"konrad.wilk@...cle.com" <konrad.wilk@...cle.com>,
"hch@....de" <hch@....de>,
"robin.murphy@....com" <robin.murphy@....com>,
"joro@...tes.org" <joro@...tes.org>,
"parri.andrea@...il.com" <parri.andrea@...il.com>,
"dave.hansen@...el.com" <dave.hansen@...el.com>
Subject: RE: [PATCH V6 7/8] Drivers: hv: vmbus: Add SNP support for VMbus
channel initiate message
From: Tianyu Lan <ltykernel@...il.com> Sent: Thursday, September 30, 2021 6:06 AM
>
> The monitor pages in the CHANNELMSG_INITIATE_CONTACT msg are shared
> with host in Isolation VM and so it's necessary to use hvcall to set
> them visible to host. In Isolation VM with AMD SEV SNP, the access
> address should be in the extra space which is above shared gpa
> boundary. So remap these pages into the extra address(pa +
> shared_gpa_boundary).
>
> Introduce monitor_pages_original[] in the struct vmbus_connection
> to store monitor page virtual address returned by hv_alloc_hyperv_
> zeroed_page() and free monitor page via monitor_pages_original in
> the vmbus_disconnect(). The monitor_pages[] is to used to access
> monitor page and it is initialized to be equal with monitor_pages_
> original. The monitor_pages[] will be overridden in the isolation VM
> with va of extra address. Introduce monitor_pages_pa[] to store
> monitor pages' physical address and use it to populate pa in the
> initiate msg.
>
> Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
> ---
> Change since v5:
> * change vmbus_connection.monitor_pages_pa type from
> unsigned long to phys_addr_t
> * Plus vmbus_connection.monitor_pages_pa with ms_hyperv.
> shared_gpa_boundary only in the IVM with AMD SEV.
>
> Change since v4:
> * Introduce monitor_pages_pa[] to store monitor pages' physical
> address and use it to populate pa in the initiate msg.
> * Move code of mapping moniter pages in extra address into
> vmbus_connect().
>
> Change since v3:
> * Rename monitor_pages_va with monitor_pages_original
> * free monitor page via monitor_pages_original and
> monitor_pages is used to access monitor page.
>
> Change since v1:
> * Not remap monitor pages in the non-SNP isolation VM.
> ---
> drivers/hv/connection.c | 90 ++++++++++++++++++++++++++++++++++++---
> drivers/hv/hyperv_vmbus.h | 2 +
> 2 files changed, 86 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index 8820ae68f20f..7fac8d99541c 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -19,6 +19,8 @@
> #include <linux/vmalloc.h>
> #include <linux/hyperv.h>
> #include <linux/export.h>
> +#include <linux/io.h>
> +#include <linux/set_memory.h>
> #include <asm/mshyperv.h>
>
> #include "hyperv_vmbus.h"
> @@ -102,8 +104,9 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
> vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
> }
>
> - msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
> - msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
> + msg->monitor_page1 = vmbus_connection.monitor_pages_pa[0];
> + msg->monitor_page2 = vmbus_connection.monitor_pages_pa[1];
> +
> msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
>
> /*
> @@ -216,6 +219,65 @@ int vmbus_connect(void)
> goto cleanup;
> }
>
> + vmbus_connection.monitor_pages_original[0]
> + = vmbus_connection.monitor_pages[0];
> + vmbus_connection.monitor_pages_original[1]
> + = vmbus_connection.monitor_pages[1];
> + vmbus_connection.monitor_pages_pa[0]
> + = virt_to_phys(vmbus_connection.monitor_pages[0]);
> + vmbus_connection.monitor_pages_pa[1]
> + = virt_to_phys(vmbus_connection.monitor_pages[1]);
> +
> + if (hv_is_isolation_supported()) {
> + ret = set_memory_decrypted((unsigned long)
> + vmbus_connection.monitor_pages[0],
> + 1);
> + ret |= set_memory_decrypted((unsigned long)
> + vmbus_connection.monitor_pages[1],
> + 1);
> + if (ret)
> + goto cleanup;
> +
> + /*
> + * Isolation VM with AMD SNP needs to access monitor page via
> + * address space above shared gpa boundary.
> + */
> + if (hv_isolation_type_snp()) {
> + vmbus_connection.monitor_pages_pa[0] +=
> + ms_hyperv.shared_gpa_boundary;
> + vmbus_connection.monitor_pages_pa[1] +=
> + ms_hyperv.shared_gpa_boundary;
> +
> + vmbus_connection.monitor_pages[0]
> + = memremap(vmbus_connection.monitor_pages_pa[0],
> + HV_HYP_PAGE_SIZE,
> + MEMREMAP_WB);
> + if (!vmbus_connection.monitor_pages[0]) {
> + ret = -ENOMEM;
> + goto cleanup;
> + }
> +
> + vmbus_connection.monitor_pages[1]
> + = memremap(vmbus_connection.monitor_pages_pa[1],
> + HV_HYP_PAGE_SIZE,
> + MEMREMAP_WB);
> + if (!vmbus_connection.monitor_pages[1]) {
> + ret = -ENOMEM;
> + goto cleanup;
> + }
> + }
> +
> + /*
> + * Set memory host visibility hvcall smears memory
> + * and so zero monitor pages here.
> + */
> + memset(vmbus_connection.monitor_pages[0], 0x00,
> + HV_HYP_PAGE_SIZE);
> + memset(vmbus_connection.monitor_pages[1], 0x00,
> + HV_HYP_PAGE_SIZE);
> +
> + }
> +
> msginfo = kzalloc(sizeof(*msginfo) +
> sizeof(struct vmbus_channel_initiate_contact),
> GFP_KERNEL);
> @@ -303,10 +365,26 @@ void vmbus_disconnect(void)
> vmbus_connection.int_page = NULL;
> }
>
> - hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[0]);
> - hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[1]);
> - vmbus_connection.monitor_pages[0] = NULL;
> - vmbus_connection.monitor_pages[1] = NULL;
> + if (hv_is_isolation_supported()) {
> + memunmap(vmbus_connection.monitor_pages[0]);
> + memunmap(vmbus_connection.monitor_pages[1]);
The matching memremap() calls are made in vmbus_connect() only in the
SNP case. In the non-SNP case, monitor_pages and monitor_pages_original
are the same, so you would be doing an unmap, and then doing the
set_memory_encrypted() and hv_free_hyperv_page() using an address
that is no longer mapped, which seems wrong. Looking at memunmap(),
it might be a no-op in this case, but even if it is, making them conditional
on the SNP case might be a safer thing to do, and it would make the code
more symmetrical.
> +
> + set_memory_encrypted((unsigned long)
> + vmbus_connection.monitor_pages_original[0],
> + 1);
> + set_memory_encrypted((unsigned long)
> + vmbus_connection.monitor_pages_original[1],
> + 1);
> + }
> +
> + hv_free_hyperv_page((unsigned long)
> + vmbus_connection.monitor_pages_original[0]);
> + hv_free_hyperv_page((unsigned long)
> + vmbus_connection.monitor_pages_original[1]);
> + vmbus_connection.monitor_pages_original[0] =
> + vmbus_connection.monitor_pages[0] = NULL;
> + vmbus_connection.monitor_pages_original[1] =
> + vmbus_connection.monitor_pages[1] = NULL;
> }
>
> /*
> diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
> index 42f3d9d123a1..d0a5232a1c3e 100644
> --- a/drivers/hv/hyperv_vmbus.h
> +++ b/drivers/hv/hyperv_vmbus.h
> @@ -240,6 +240,8 @@ struct vmbus_connection {
> * is child->parent notification
> */
> struct hv_monitor_page *monitor_pages[2];
> + void *monitor_pages_original[2];
> + phys_addr_t monitor_pages_pa[2];
> struct list_head chn_msg_list;
> spinlock_t channelmsg_lock;
>
> --
> 2.25.1
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