diff mbox series

[RFC,V2,11/18] Drivers: hv: vmbus: Decrypt vmbus ring buffer

Message ID 20221119034633.1728632-12-ltykernel@gmail.com
State New
Headers
Series x86/hyperv/sev: Add AMD sev-snp enlightened guest support on hyperv |

Commit Message

Tianyu Lan Nov. 19, 2022, 3:46 a.m. UTC 
  From: Tianyu Lan <tiala@microsoft.com>

The ring buffer is remapped in the hv_ringbuffer_init()
and it should be with decrypt flag in order to share it
with hypervisor in sev-snp enlightened guest.

Signed-off-by: Tianyu Lan <tiala@microsoft.com>
---
 drivers/hv/ring_buffer.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

Michael Kelley (LINUX) Dec. 14, 2022, 6:25 p.m. UTC | #1 
From: Tianyu Lan <ltykernel@gmail.com> Sent: Friday, November 18, 2022 7:46 PM
> 
> The ring buffer is remapped in the hv_ringbuffer_init()
> and it should be with decrypt flag in order to share it
> with hypervisor in sev-snp enlightened guest.

FWIW, the change in this patch is included in Patch 9
in my vTOM-related patch series.

> 
> Signed-off-by: Tianyu Lan <tiala@microsoft.com>
> ---
>  drivers/hv/ring_buffer.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
> index 59a4aa86d1f3..391995c76be7 100644
> --- a/drivers/hv/ring_buffer.c
> +++ b/drivers/hv/ring_buffer.c
> @@ -18,6 +18,7 @@
>  #include <linux/slab.h>
>  #include <linux/prefetch.h>
>  #include <linux/io.h>
> +#include <linux/set_memory.h>
>  #include <asm/mshyperv.h>
> 
>  #include "hyperv_vmbus.h"
> @@ -233,14 +234,18 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
> 
>  		ring_info->ring_buffer = (struct hv_ring_buffer *)
>  			vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP,
> +				hv_isolation_type_en_snp() ?
> +				pgprot_decrypted(PAGE_KERNEL_NOENC) :
>  				PAGE_KERNEL);

Note that pgprot_decrypted(PAGE_KERNEL_NOENC) can always be
used, as it does nothing in a normal VM.  Its use doesn't need to be
conditional on the isolation type.

> 
> +		if (hv_isolation_type_en_snp())
> +			memset(ring_info->ring_buffer, 0x00, page_cnt * PAGE_SIZE);

My version of the change always does the zero'ing, but only of
the first page, as Hyper-V expects the ring buffer header page to be
clean.  The initial contents of the rest of the ring buffer doesn't
really matter.

> +
>  		kfree(pages_wraparound);
>  		if (!ring_info->ring_buffer)
>  			return -ENOMEM;
>  	}
> 
> -

The above looks like a spurious whitespace change.

>  	ring_info->ring_buffer->read_index =
>  		ring_info->ring_buffer->write_index = 0;
> 
> --
> 2.25.1
Tianyu Lan Dec. 26, 2022, 7:59 a.m. UTC | #2 
On 12/15/2022 2:25 AM, Michael Kelley (LINUX) wrote:
> From: Tianyu Lan<ltykernel@gmail.com>  Sent: Friday, November 18, 2022 7:46 PM
>> The ring buffer is remapped in the hv_ringbuffer_init()
>> and it should be with decrypt flag in order to share it
>> with hypervisor in sev-snp enlightened guest.
> FWIW, the change in this patch is included in Patch 9
> in my vTOM-related patch series.
> 

I will rebase next version on your series. Thanks for reminder.
diff mbox series

Patch

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 59a4aa86d1f3..391995c76be7 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -18,6 +18,7 @@ 
 #include <linux/slab.h>
 #include <linux/prefetch.h>
 #include <linux/io.h>
+#include <linux/set_memory.h>
 #include <asm/mshyperv.h>
 
 #include "hyperv_vmbus.h"
@@ -233,14 +234,18 @@  int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
 
 		ring_info->ring_buffer = (struct hv_ring_buffer *)
 			vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP,
+				hv_isolation_type_en_snp() ?
+				pgprot_decrypted(PAGE_KERNEL_NOENC) :
 				PAGE_KERNEL);
 
+		if (hv_isolation_type_en_snp())
+			memset(ring_info->ring_buffer, 0x00, page_cnt * PAGE_SIZE);
+
 		kfree(pages_wraparound);
 		if (!ring_info->ring_buffer)
 			return -ENOMEM;
 	}
 
-
 	ring_info->ring_buffer->read_index =
 		ring_info->ring_buffer->write_index = 0;