On 5/30/2024 7:33 PM, Tom Lendacky wrote: > On 5/23/24 07:18, Ravi Bangoria wrote: >> As documented in APM[1], LBR Virtualization must be enabled for SEV-ES >> guests. Although KVM currently enforces LBRV for SEV-ES guests, there >> are multiple issues with it: >> >> o MSR_IA32_DEBUGCTLMSR is still intercepted. Since MSR_IA32_DEBUGCTLMSR >> interception is used to dynamically toggle LBRV for performance reasons, >> this can be fatal for SEV-ES guests. For ex SEV-ES guest on Zen3: >> >> [guest ~]# wrmsr 0x1d9 0x4 >> KVM: entry failed, hardware error 0xffffffff >> EAX=00000004 EBX=00000000 ECX=000001d9 EDX=00000000 >> >> Fix this by never intercepting MSR_IA32_DEBUGCTLMSR for SEV-ES guests. >> No additional save/restore logic is required since MSR_IA32_DEBUGCTLMSR >> is of swap type A. >> >> o KVM will disable LBRV if userspace sets MSR_IA32_DEBUGCTLMSR before the >> VMSA is encrypted. Fix this by moving LBRV enablement code post VMSA >> encryption. >> >> [1]: AMD64 Architecture Programmer's Manual Pub. 40332, Rev. 4.07 - June >> 2023, Vol 2, 15.35.2 Enabling SEV-ES. >> https://bugzilla.kernel.org/attachment.cgi?id=304653 >> >> Co-developed-by: Nikunj A Dadhania <nikunj@xxxxxxx> >> Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx> >> Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx> > > Should this have a Fixes: tag, too? Yeah, will add Fixes: 376c6d285017 ("KVM: SVM: Provide support for SEV-ES vCPU creation/loading") Thanks, Ravi
