mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-23 11:04:44 +08:00
c3f08ed150
On guest exit MSR_GS_BASE contains whatever the guest wrote to it and the first action after returning from the ASM code is to set it to the host kernel value. This uses wrmsrl() which is interesting at least. wrmsrl() is either using native_write_msr() or the paravirt variant. The XEN_PV code is uninteresting as nested SVM in a XEN_PV guest does not work. But native_write_msr() can be placed out of line by the compiler especially when paravirtualization is enabled in the kernel configuration. The function is marked notrace, but still can be probed if CONFIG_KPROBE_EVENTS_ON_NOTRACE is enabled. That would be a fatal problem as kprobe events use per-CPU variables which are GS based and would be accessed with the guest GS. Depending on the GS value this would either explode in colorful ways or lead to completely undebugable data corruption. Aside of that native_write_msr() contains a tracepoint which objtool complains about as it is invoked from the noinstr section. As this cannot run inside a XEN_PV guest there is no point in using wrmsrl(). Use native_wrmsrl() instead which is just a plain native WRMSR without tracing or anything else attached. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Juergen Gross <jgross@suse.com> Message-Id: <20200708195322.244847377@linutronix.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
||
|---|---|---|
| .. | ||
| avic.c | ||
| nested.c | ||
| pmu.c | ||
| sev.c | ||
| svm.c | ||
| svm.h | ||
| vmenter.S | ||