On Sun, Jun 11, 2023 at 11:25:15PM -0500, Michael Roth wrote: > From: Brijesh Singh <brijesh.singh@xxxxxxx> > > The memory integrity guarantees of SEV-SNP are enforced through a new > structure called the Reverse Map Table (RMP). The RMP is a single data > structure shared across the system that contains one entry for every 4K > page of DRAM that may be used by SEV-SNP VMs. APM2 section 15.36 details Rather say 'APM v2, section "Secure Nested Paging (SEV-SNP)"' because the numbering is more likely to change than the name in the future. With the name, people can find it faster. > a number of steps needed to detect/enable SEV-SNP and RMP table support > on the host: > > - Detect SEV-SNP support based on CPUID bit > - Initialize the RMP table memory reported by the RMP base/end MSR > registers and configure IOMMU to be compatible with RMP access > restrictions > - Set the MtrrFixDramModEn bit in SYSCFG MSR > - Set the SecureNestedPagingEn and VMPLEn bits in the SYSCFG MSR > - Configure IOMMU > > RMP table entry format is non-architectural and it can vary by > processor. It is defined by the PPR. Restrict SNP support to CPU > models/families which are compatible with the current RMP table entry > format to guard against any undefined behavior when running on other > system types. Future models/support will handle this through an > architectural mechanism to allow for broader compatibility. I'm guessing this is all for live migration between SNP hosts. If so, then there will have to be a guest API to handle the differences. > SNP host code depends on CONFIG_KVM_AMD_SEV config flag, which may be > enabled even when CONFIG_AMD_MEM_ENCRYPT isn't set, so update the > SNP-specific IOMMU helpers used here to rely on CONFIG_KVM_AMD_SEV > instead of CONFIG_AMD_MEM_ENCRYPT. Does that mean that even on CONFIG_AMD_MEM_ENCRYPT=n kernels, host SNP can function? Do we even want that? I'd expect that a host SNP kernel should have SME enabled too even though it is not absolutely necessary. > Co-developed-by: Ashish Kalra <ashish.kalra@xxxxxxx> > Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx> > Co-developed-by: Tom Lendacky <thomas.lendacky@xxxxxxx> > Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx> > Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx> > [mdr: rework commit message to be clearer about what patch does, squash > in early_rmptable_check() handling from Tom] > Signed-off-by: Michael Roth <michael.roth@xxxxxxx> > --- > arch/x86/coco/Makefile | 1 + > arch/x86/coco/sev/Makefile | 3 + > arch/x86/coco/sev/host.c | 212 +++++++++++++++++++++++ > arch/x86/include/asm/disabled-features.h | 8 +- > arch/x86/include/asm/msr-index.h | 11 +- > arch/x86/include/asm/sev.h | 2 + > arch/x86/kernel/cpu/amd.c | 19 ++ > drivers/iommu/amd/init.c | 2 +- > include/linux/amd-iommu.h | 2 +- > 9 files changed, 256 insertions(+), 4 deletions(-) > create mode 100644 arch/x86/coco/sev/Makefile > create mode 100644 arch/x86/coco/sev/host.c Ignored review comments here: https://lore.kernel.org/r/Y9ubi0i4Z750gdMm@xxxxxxx Ignoring this one for now too. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
