| Message ID | cover.1598382343.git.thomas.lendacky@amd.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | SEV-ES guest support | expand |
On 8/25/20 2:05 PM, Tom Lendacky wrote: > From: Tom Lendacky <thomas.lendacky@amd.com> > > This patch series provides support for launching an SEV-ES guest. I've made the changes associated with the checkpatch script output. I'll wait a few more days for other feedback before submitting a v2. Sorry about the miss in regards to running checkpatch. Thanks, Tom > > 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]. > > The main areas of the Qemu code that are updated to support SEV-ES are > around the SEV guest launch process and AP booting in order to support > booting multiple vCPUs. > > There are no new command line switches required. Instead, the desire for > SEV-ES is presented using the SEV policy object. Bit 2 of the SEV policy > object indicates that SEV-ES is required. > > The SEV launch process is updated in two ways. The first is that a the > KVM_SEV_ES_INIT ioctl is used to initialize the guest instead of the > standard KVM_SEV_INIT ioctl. The second is that before the SEV launch > measurement is calculated, the LAUNCH_UPDATE_VMSA SEV API is invoked for > each vCPU that Qemu has created. Once the LAUNCH_UPDATE_VMSA API has been > invoked, no direct changes to the guest register state can be made. > > AP booting poses some interesting challenges. The INIT-SIPI-SIPI sequence > is typically used to boot the APs. However, the hypervisor is not allowed > to update the guest registers. For the APs, the reset vector must be known > in advance. An OVMF method to provide a known reset vector address exists > by providing an SEV information block, identified by UUID, near the end of > the firmware [3]. OVMF will program the jump to the actual reset vector in > this area of memory. Since the memory location is known in advance, an AP > can be created with the known reset vector address as its starting CS:IP. > The GHCB document [2] talks about how SMP booting under SEV-ES is > performed. > > [1] https://www.amd.com/system/files/TechDocs/24593.pdf > [2] https://developer.amd.com/wp-content/resources/56421.pdf > [3] 30937f2f98c4 ("OvmfPkg: Use the SEV-ES work area for the SEV-ES AP reset vector") > https://github.com/tianocore/edk2/commit/30937f2f98c42496f2f143fe8374ae7f7e684847 > > --- > > These patches are based on commit: > d0ed6a69d3 ("Update version for v5.1.0 release") > > (I tried basing on the latest Qemu commit, but I was having build issues > that level) > > A version of the tree can be found at: > https://github.com/AMDESE/qemu/tree/sev-es-v9 > > Tom Lendacky (4): > sev/i386: Add initial support for SEV-ES > sev/i386: Allow AP booting under SEV-ES > sev/i386: Don't allow a system reset under an SEV-ES guest > sev/i386: Enable an SEV-ES guest based on SEV policy > > accel/kvm/kvm-all.c | 68 ++++++++++++++++++++++++++++ > accel/stubs/kvm-stub.c | 5 +++ > hw/i386/pc_sysfw.c | 10 ++++- > include/sysemu/cpus.h | 2 + > include/sysemu/hw_accel.h | 4 ++ > include/sysemu/kvm.h | 18 ++++++++ > include/sysemu/sev.h | 2 + > softmmu/cpus.c | 5 +++ > softmmu/vl.c | 5 ++- > target/i386/cpu.c | 1 + > target/i386/kvm.c | 2 + > target/i386/sev-stub.c | 5 +++ > target/i386/sev.c | 95 ++++++++++++++++++++++++++++++++++++++- > target/i386/sev_i386.h | 1 + > 14 files changed, 219 insertions(+), 4 deletions(-) >
From: Tom Lendacky <thomas.lendacky@amd.com> This patch series provides support for launching an SEV-ES guest. 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]. The main areas of the Qemu code that are updated to support SEV-ES are around the SEV guest launch process and AP booting in order to support booting multiple vCPUs. There are no new command line switches required. Instead, the desire for SEV-ES is presented using the SEV policy object. Bit 2 of the SEV policy object indicates that SEV-ES is required. The SEV launch process is updated in two ways. The first is that a the KVM_SEV_ES_INIT ioctl is used to initialize the guest instead of the standard KVM_SEV_INIT ioctl. The second is that before the SEV launch measurement is calculated, the LAUNCH_UPDATE_VMSA SEV API is invoked for each vCPU that Qemu has created. Once the LAUNCH_UPDATE_VMSA API has been invoked, no direct changes to the guest register state can be made. AP booting poses some interesting challenges. The INIT-SIPI-SIPI sequence is typically used to boot the APs. However, the hypervisor is not allowed to update the guest registers. For the APs, the reset vector must be known in advance. An OVMF method to provide a known reset vector address exists by providing an SEV information block, identified by UUID, near the end of the firmware [3]. OVMF will program the jump to the actual reset vector in this area of memory. Since the memory location is known in advance, an AP can be created with the known reset vector address as its starting CS:IP. The GHCB document [2] talks about how SMP booting under SEV-ES is performed. [1] https://www.amd.com/system/files/TechDocs/24593.pdf [2] https://developer.amd.com/wp-content/resources/56421.pdf [3] 30937f2f98c4 ("OvmfPkg: Use the SEV-ES work area for the SEV-ES AP reset vector") https://github.com/tianocore/edk2/commit/30937f2f98c42496f2f143fe8374ae7f7e684847 --- These patches are based on commit: d0ed6a69d3 ("Update version for v5.1.0 release") (I tried basing on the latest Qemu commit, but I was having build issues that level) A version of the tree can be found at: https://github.com/AMDESE/qemu/tree/sev-es-v9 Tom Lendacky (4): sev/i386: Add initial support for SEV-ES sev/i386: Allow AP booting under SEV-ES sev/i386: Don't allow a system reset under an SEV-ES guest sev/i386: Enable an SEV-ES guest based on SEV policy accel/kvm/kvm-all.c | 68 ++++++++++++++++++++++++++++ accel/stubs/kvm-stub.c | 5 +++ hw/i386/pc_sysfw.c | 10 ++++- include/sysemu/cpus.h | 2 + include/sysemu/hw_accel.h | 4 ++ include/sysemu/kvm.h | 18 ++++++++ include/sysemu/sev.h | 2 + softmmu/cpus.c | 5 +++ softmmu/vl.c | 5 ++- target/i386/cpu.c | 1 + target/i386/kvm.c | 2 + target/i386/sev-stub.c | 5 +++ target/i386/sev.c | 95 ++++++++++++++++++++++++++++++++++++++- target/i386/sev_i386.h | 1 + 14 files changed, 219 insertions(+), 4 deletions(-)