On 10/12/20 18:09, Tom Lendacky wrote:
From: Tom Lendacky <thomas.lendacky@xxxxxxx> This patch series provides support for running SEV-ES guests under KVM. Secure Encrypted Virtualization - Encrypted State (SEV-ES) expands on the SEV support to protect the guest register state from the hypervisor. See "AMD64 Architecture Programmer's Manual Volume 2: System Programming", section "15.35 Encrypted State (SEV-ES)" [1]. In order to allow a hypervisor to perform functions on behalf of a guest, there is architectural support for notifying a guest's operating system when certain types of VMEXITs are about to occur. This allows the guest to selectively share information with the hypervisor to satisfy the requested function. The notification is performed using a new exception, the VMM Communication exception (#VC). The information is shared through the Guest-Hypervisor Communication Block (GHCB) using the VMGEXIT instruction. The GHCB format and the protocol for using it is documented in "SEV-ES Guest-Hypervisor Communication Block Standardization" [2]. Under SEV-ES, a vCPU save area (VMSA) must be encrypted. SVM is updated to build the initial VMSA and then encrypt it before running the guest. Once encrypted, it must not be modified by the hypervisor. Modification of the VMSA will result in the VMRUN instruction failing with a SHUTDOWN exit code. KVM must support the VMGEXIT exit code in order to perform the necessary functions required of the guest. The GHCB is used to exchange the information needed by both the hypervisor and the guest. Register data from the GHCB is copied into the KVM register variables and accessed as usual during handling of the exit. Upon return to the guest, updated registers are copied back to the GHCB for the guest to act upon. There are changes to some of the intercepts that are needed under SEV-ES. For example, CR0 writes cannot be intercepted, so the code needs to ensure that the intercept is not enabled during execution or that the hypervisor does not try to read the register as part of exit processing. Another example is shutdown processing, where the vCPU cannot be directly reset. Support is added to handle VMGEXIT events and implement the GHCB protocol. This includes supporting standard exit events, like a CPUID instruction intercept, to new support, for things like AP processor booting. Much of the existing SVM intercept support can be re-used by setting the exit code information from the VMGEXIT and calling the appropriate intercept handlers. Finally, to launch and run an SEV-ES guest requires changes to the vCPU initialization, loading and execution. [1] https://www.amd.com/system/files/TechDocs/24593.pdf [2] https://developer.amd.com/wp-content/resources/56421.pdf --- These patches are based on the KVM queue branch: https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue dc924b062488 ("KVM: SVM: check CR4 changes against vcpu->arch") A version of the tree can also be found at: https://github.com/AMDESE/linux/tree/sev-es-v5 This tree has one addition patch that is not yet part of the queue tree that is required to run any SEV guest: [PATCH] KVM: x86: adjust SEV for commit 7e8e6eed75e https://lore.kernel.org/kvm/20201130143959.3636394-1-pbonzini@xxxxxxxxxx/ Changes from v4: - Updated the tracking support for CR0/CR4 Changes from v3: - Some krobot fixes. - Some checkpatch cleanups. Changes from v2: - Update the freeing of the VMSA page to account for the encrypted memory cache coherency feature as well as the VM page flush feature. - Update the GHCB dump function with a bit more detail. - Don't check for RAX being present as part of a string IO operation. - Include RSI when syncing from GHCB to support KVM hypercall arguments. - Add GHCB usage field validation check. Changes from v1: - Removed the VMSA indirection support: - On LAUNCH_UPDATE_VMSA, sync traditional VMSA over to the new SEV-ES VMSA area to be encrypted. - On VMGEXIT VMEXIT, directly copy valid registers into vCPU arch register array from GHCB. On VMRUN (following a VMGEXIT), directly copy dirty vCPU arch registers to GHCB. - Removed reg_read_override()/reg_write_override() KVM ops. - Added VMGEXIT exit-reason validation. - Changed kvm_vcpu_arch variable vmsa_encrypted to guest_state_protected - Updated the tracking support for EFER/CR0/CR4/CR8 to minimize changes to the x86.c code - Updated __set_sregs to not set any register values (previously supported setting the tracked values of EFER/CR0/CR4/CR8) - Added support for reporting SMM capability at the VM-level. This allows an SEV-ES guest to indicate SMM is not supported - Updated FPU support to check for a guest FPU save area before using it. Updated SVM to free guest FPU for an SEV-ES guest during KVM create_vcpu op. - Removed changes to the kvm_skip_emulated_instruction() - Added VMSA validity checks before invoking LAUNCH_UPDATE_VMSA - Minor code restructuring in areas for better readability Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Jim Mattson <jmattson@xxxxxxxxxx> Cc: Joerg Roedel <joro@xxxxxxxxxx> Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Cc: Wanpeng Li <wanpengli@xxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Brijesh Singh <brijesh.singh@xxxxxxx>
I'm queuing everything except patch 27, there's time to include it later in 5.11.
Regarding MSRs, take a look at the series I'm sending shortly (or perhaps in a couple hours). For now I'll keep it in kvm/queue, but the plan is to get acks quickly and/or just include it in 5.11. Please try the kvm/queue branch to see if I screwed up anything.
Paolo
