Messages in this thread | | | Date | Mon, 26 Feb 2024 14:02:32 -0600 | Subject | Re: [PATCH 0/8] KVM: SVM: Clean up VMRUN=>#VMEXIT assembly | From | Tom Lendacky <> |
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On 2/23/24 14:42, Sean Christopherson wrote: > 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(-)
Nice cleanup, thanks!
For the series: Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
> > > base-commit: ec1e3d33557babed2c2c2c7da6e84293c2f56f58
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