| Message ID | 20210602140416.23573-13-brijesh.singh@amd.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Guest Support | expand |
On Wed, Jun 02, 2021 at 09:04:06AM -0500, 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 de01903c3735..f4c3e632345a 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -288,7 +288,14 @@ unsigned long __head __startup_64(unsigned long physaddr, > if (mem_encrypt_active()) { > 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); > + > i = pmd_index(vaddr); > pmd[i] -= sme_get_me_mask(); > } > -- It seems to me that all that code from the sme_encrypt_kernel(bp); call to the end of the function should be in a separate function in sev.c called sev_prepare_kernel(...args...) to be at least abstracted away from the main boot path. Thx.
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index de01903c3735..f4c3e632345a 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -288,7 +288,14 @@ unsigned long __head __startup_64(unsigned long physaddr, if (mem_encrypt_active()) { 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); + i = pmd_index(vaddr); pmd[i] -= sme_get_me_mask(); }
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(+)