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Message-ID: <20230811101456.GDZNYKIHs1k7ri8hrI@fat_crate.local>
Date: Fri, 11 Aug 2023 12:14:56 +0200
From: Borislav Petkov <bp@...en8.de>
To: Nathan Chancellor <nathan@...nel.org>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: Hang when booting guest kernels compiled with clang after SRSO
mitigations
On Thu, Aug 10, 2023 at 09:14:14AM -0700, Nathan Chancellor wrote:
> Not sure how helpful that will be...
Yeah, not really. More wild guesses: if you uncomment the UNTRAIN_RET in
__svm_vcpu_run() on the host, does that have any effect? Diff below.
Also, can you send me the host and guest .configs and the compilers
you've used so that I can try to reproduce here exactly what you have?
Thx.
---
diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S
index 265452fc9ebe..b5871259a973 100644
--- a/arch/x86/kvm/svm/vmenter.S
+++ b/arch/x86/kvm/svm/vmenter.S
@@ -222,7 +222,7 @@ SYM_FUNC_START(__svm_vcpu_run)
* because interrupt handlers won't sanitize 'ret' if the return is
* from the kernel.
*/
- UNTRAIN_RET
+// UNTRAIN_RET
/* SRSO */
ALTERNATIVE "", "call entry_ibpb", X86_FEATURE_IBPB_ON_VMEXIT
--
Regards/Gruss,
Boris.
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