Re: [RFC PATCH V5 05/15] clocksource/drivers/hyper-v: decrypt hyperv tsc page in sev-snp enlightened guest

Zhi Wang
2023-05-04T16:55:00Z

On Mon, 1 May 2023 04:57:15 -0400
Tianyu Lan <ltykernel@gmail.com> wrote:

> From: Tianyu Lan <tiala@microsoft.com>
>
> Hyper-V tsc page is shared with hypervisor and it should
> be decrypted in sev-snp enlightened guest when it's used.
>
> Signed-off-by: Tianyu Lan <tiala@microsoft.com>
> ---
> Change since RFC V2:
> * Change the Subject line prefix
> ---
> drivers/clocksource/hyperv_timer.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
> index bcd9042a0c9f..66e29a19770b 100644
> --- a/drivers/clocksource/hyperv_timer.c
> +++ b/drivers/clocksource/hyperv_timer.c
> @@ -376,7 +376,7 @@ EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
> static union {
> struct ms_hyperv_tsc_page page;
> u8 reserved[PAGE_SIZE];
> -} tsc_pg __aligned(PAGE_SIZE);
> +} tsc_pg __bss_decrypted __aligned(PAGE_SIZE);
>

Out of curiosity, this is not a on/off for VM with paravisor and full-enlightened VM, how
does change affect the case of VM with paravisor? I assume the VM with paravisor works fine
without this previously.

> static struct ms_hyperv_tsc_page *tsc_page = &tsc_pg.page;
> static unsigned long tsc_pfn;