Re: [PATCH v8 13/40] x86/kernel: Make the bss.decrypted section shared in RMP table

Venu Busireddy
2022-01-04T17:57:12Z

On 2021-12-10 09:43:05 -0600, Brijesh Singh wrote:
> The encryption attribute for the bss.decrypted region is cleared in the
> initial page table build. This is because the section contains the data
> that need to be shared between the guest and the hypervisor.
>
> When SEV-SNP is active, just clearing the encryption attribute in the
> page table is not enough. The page state need to be updated in the RMP
> table.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
> arch/x86/kernel/head64.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index fa02402dcb9b..72c5082a3ba4 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -143,7 +143,14 @@ static unsigned long sme_postprocess_startup(struct boot_params *bp, pmdval_t *p
> if (sme_get_me_mask()) {
> vaddr = (unsigned long)__start_bss_decrypted;
> vaddr_end = (unsigned long)__end_bss_decrypted;
> +
> for (; vaddr < vaddr_end; vaddr += PMD_SIZE) {
> + /*
> + * When SEV-SNP is active then transition the page to shared in the RMP
> + * table so that it is consistent with the page table attribute change.
> + */
> + early_snp_set_memory_shared(__pa(vaddr), __pa(vaddr), PTRS_PER_PMD);

Shouldn't the first argument be vaddr as below?

early_snp_set_memory_shared(vaddr, __pa(vaddr), PTRS_PER_PMD);

Venu