From: Brijesh Singh Date: Wed, 9 Feb 2022 12:10:13 -0600 Subject: x86/kernel: Mark the .bss..decrypted section as shared in the RMP table Git-commit: efac0eedfab515e523cde5cb7a62289eb2ee58f8 Patch-mainline: v5.19-rc1 References: jsc#SLE-19924, jsc#SLE-24814 The encryption attribute for the .bss..decrypted section 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 needs to be updated in the RMP table. Signed-off-by: Brijesh Singh Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220307213356.2797205-20-brijesh.singh@amd.com Acked-by: Joerg Roedel --- arch/x86/kernel/head64.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -143,7 +143,20 @@ static unsigned long sme_postprocess_sta 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) { + /* + * On SNP, transition the page to shared in the RMP table so that + * it is consistent with the page table attribute change. + * + * __start_bss_decrypted has a virtual address in the high range + * mapping (kernel .text). PVALIDATE, by way of + * early_snp_set_memory_shared(), requires a valid virtual + * address but the kernel is currently running off of the identity + * mapping so use __pa() to get a *currently* valid virtual address. + */ + early_snp_set_memory_shared(__pa(vaddr), __pa(vaddr), PTRS_PER_PMD); + i = pmd_index(vaddr); pmd[i] -= sme_get_me_mask(); }