From: Jun Miao <jun.miao@intel.com>
To: kirill.shutemov@linux.intel.com, ave.hansen@linux.intel.com
Cc: x86@kernel.org, linux-coco@lists.linux.dev, jun.miao@intel.com,
fan.du@intel.com, zhiquan1.li@intel.com
Subject: [PATCH 0/1][Bug Report] and fix TDX cpuid0x2 #VE causing segfault
Date: Tue, 29 Apr 2025 09:29:17 -0400 [thread overview]
Message-ID: <20250429132918.1284811-1-jun.miao@intel.com> (raw)
Hi
[TDX Bug Report]
There is a segfault, when boot a upstream kernel as TDX guest.
- Boot log:
[ 46.902055] systemd[1]: segfault at 55c974b82650 ip 00007f252eef09c2 sp 00007ffcd94fe7b8 error 4 in libc.so.6[7f252ee28000+175000] likely on CPU 1 (core 1, socket 0)
[ 46.903302] Code: 00 0f 18 8e 00 31 00 00 0f 18 8e 40 31 00 00 0f 18 8e 80 31 00 00 0f 18 8e c0 31 00 00 62 e1 fe 48 6f 06 62 e1 fe 48 6f 4e 01 <62> e1 fe 48 6f 66 40 62 e1 fe 48 6f 6e 41 62 61 fe 48 6f 86 00 20
[ 46.905516] systemd[1]: Caught <SEGV> from PID 1958225488.
[ 46.921256] systemd[1]: Caught <SEGV>, dumped core as pid 346.
[ 46.922056] systemd[1]: Freezing execution.
- Gest kernel version:
Linux version 6.15.0-rc4
- Guest qcow2:
rhel-guest-image-9.2-20230414.17.x86_64.qcow2
- TDX module info:
TDX module: 1.5.16.00.0869 (build_date 20250219, Production module), TDX_FEATURES0 0x226f3f0fbf
TDX_FEATURES0.VE_REDUCTION (bit 30) = 1
TDX_FEATURES0.CPUID2_VIRT (bit 29) = 1
The root cases:
Glibc 2.34 and newer segfault if CPUID leaf 0x2 reports zero.
https://sourceware.org/bugzilla/show_bug.cgi?id=30037
That is #VE on CPUID leaf 0x2 is handled by returning all-0 to the code which executed CPUID.
In many cases, an all-0 value is not the correct value, and may cause improper operation.
Although, the bits of VE_REDUCETION and VIRT_CPUID2 are marked "1" as supported in TDX FEATURES0, their functionality fails during runtime stress tests.
[Solution]
Add VIRT_CPUID2 virtualization if REDUCE_VE was not successful to avoiding the segfault when glibc invoked the CPUID leaf 0x2.
Since the enable_cpu_topology_enumeration() was very little and can be integrated into reduce_unnecessary_ve().
[PATCH 1/1] x86/tdx: add VIRT_CPUID2 virtualization if REDUCE_VE was not successful
*** ***
Zhiquan Li (1):
x86/tdx: add VIRT_CPUID2 virtualization if REDUCE_VE was not
successful
arch/x86/coco/tdx/tdx.c | 56 +++++++++++++++++++++++++----------------
1 file changed, 35 insertions(+), 21 deletions(-)
--
2.43.0
next reply other threads:[~2025-04-29 5:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-29 13:29 Jun Miao [this message]
2025-04-29 13:29 ` [PATCH 1/1] x86/tdx: add VIRT_CPUID2 virtualization if REDUCE_VE was not successful Jun Miao
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