Messages in this thread | | | Date | Fri, 23 Feb 2024 12:42:25 -0800 | Subject | [PATCH 0/8] KVM: SVM: Clean up VMRUN=>#VMEXIT assembly | From | Sean Christopherson <> |
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Clean up SVM's enter/exit assembly code so that it can be compiled without OBJECT_FILES_NON_STANDARD. The "standard" __svm_vcpu_run() can't be made 100% bulletproof, as RBP isn't restored on #VMEXIT, but that's also the case for __vmx_vcpu_run(), and getting "close enough" is better than not even trying.
As for SEV-ES, after yet another refresher on swap types, I realized KVM can simply let the hardware restore registers after #VMEXIT, all that's missing is storing the current values to the host save area (I learned the hard way that they are swap Type B, *sigh*). Unless I'm missing something, this provides 100% accuracy when using stack frames for unwinding, and requires less assembly (though probably not fewer code bytes; I didn't check).
In between, build the SEV-ES code iff CONFIG_KVM_AMD_SEV=y, and yank out "support" for 32-bit kernels, which was unncessarily polluting the code.
I'm pretty sure I actually managed to test all of this, thanks to the SEV-ES smoke selftests, and a bit of hacking to disable V_SPEC_CTRL, passthrough SPEC_CTRL unconditionally, and have the selftests W/R SPEC_CTRL from its guest.
Sean Christopherson (8): KVM: SVM: Create a stack frame in __svm_vcpu_run() for unwinding KVM: SVM: Wrap __svm_sev_es_vcpu_run() with #ifdef CONFIG_KVM_AMD_SEV KVM: SVM: Drop 32-bit "support" from __svm_sev_es_vcpu_run() KVM: SVM: Clobber RAX instead of RBX when discarding spec_ctrl_intercepted KVM: SVM: Save/restore non-volatile GPRs in SEV-ES VMRUN via host save area KVM: SVM: Save/restore args across SEV-ES VMRUN via host save area KVM: SVM: Create a stack frame in __svm_sev_es_vcpu_run() KVM: x86: Stop compiling vmenter.S with OBJECT_FILES_NON_STANDARD
arch/x86/kvm/Makefile | 4 -- arch/x86/kvm/svm/svm.c | 17 ++++--- arch/x86/kvm/svm/svm.h | 3 +- arch/x86/kvm/svm/vmenter.S | 97 +++++++++++++++++--------------------- 4 files changed, 56 insertions(+), 65 deletions(-)
base-commit: ec1e3d33557babed2c2c2c7da6e84293c2f56f58 -- 2.44.0.rc0.258.g7320e95886-goog
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