| Message ID | 20210707181506.30489-14-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, Jul 07, 2021 at 01:14:43PM -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(+) Please apply this cleanup before this one. Thx. --- From: Borislav Petkov <bp@suse.de> Subject: [PATCH] x86/head64: Carve out the guest encryption postprocessing into a helper Carve it out so that it is abstracted out of the main boot path. All other encrypted guest-relevant processing should be placed in there. No functional changes. Signed-off-by: Borislav Petkov <bp@suse.de> --- arch/x86/kernel/head64.c | 55 ++++++++++++++++++++++------------------ 1 file changed, 31 insertions(+), 24 deletions(-) diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index de01903c3735..eee24b427237 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -126,6 +126,36 @@ static bool __head check_la57_support(unsigned long physaddr) } #endif +static unsigned long sme_postprocess_startup(struct boot_params *bp, pmdval_t *pmd) +{ + unsigned long vaddr, vaddr_end; + int i; + + /* Encrypt the kernel and related (if SME is active) */ + sme_encrypt_kernel(bp); + + /* + * Clear the memory encryption mask from the .bss..decrypted section. + * The bss section will be memset to zero later in the initialization so + * there is no need to zero it after changing the memory encryption + * attribute. + */ + if (mem_encrypt_active()) { + vaddr = (unsigned long)__start_bss_decrypted; + vaddr_end = (unsigned long)__end_bss_decrypted; + for (; vaddr < vaddr_end; vaddr += PMD_SIZE) { + i = pmd_index(vaddr); + pmd[i] -= sme_get_me_mask(); + } + } + + /* + * Return the SME encryption mask (if SME is active) to be used as a + * modifier for the initial pgdir entry programmed into CR3. + */ + return sme_get_me_mask(); +} + /* Code in __startup_64() can be relocated during execution, but the compiler * doesn't have to generate PC-relative relocations when accessing globals from * that function. Clang actually does not generate them, which leads to @@ -135,7 +165,6 @@ static bool __head check_la57_support(unsigned long physaddr) unsigned long __head __startup_64(unsigned long physaddr, struct boot_params *bp) { - unsigned long vaddr, vaddr_end; unsigned long load_delta, *p; unsigned long pgtable_flags; pgdval_t *pgd; @@ -276,29 +305,7 @@ unsigned long __head __startup_64(unsigned long physaddr, */ *fixup_long(&phys_base, physaddr) += load_delta - sme_get_me_mask(); - /* Encrypt the kernel and related (if SME is active) */ - sme_encrypt_kernel(bp); - - /* - * Clear the memory encryption mask from the .bss..decrypted section. - * The bss section will be memset to zero later in the initialization so - * there is no need to zero it after changing the memory encryption - * attribute. - */ - if (mem_encrypt_active()) { - vaddr = (unsigned long)__start_bss_decrypted; - vaddr_end = (unsigned long)__end_bss_decrypted; - for (; vaddr < vaddr_end; vaddr += PMD_SIZE) { - i = pmd_index(vaddr); - pmd[i] -= sme_get_me_mask(); - } - } - - /* - * Return the SME encryption mask (if SME is active) to be used as a - * modifier for the initial pgdir entry programmed into CR3. - */ - return sme_get_me_mask(); + return sme_postprocess_startup(bp, pmd); } unsigned long __startup_secondary_64(void)
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(+)