[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 1/4] x86/vmx: Don't leak host syscall MSR state into HVM guests
On 14/02/2017 08:04, Tian, Kevin wrote: >> From: Andrew Cooper [mailto:amc96@xxxxxxxxxxxxxxxx] On Behalf Of Andrew >> Cooper >> Sent: Tuesday, February 14, 2017 3:59 PM >> >> On 14/02/2017 02:52, Tian, Kevin wrote: >>>> From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx] >>>> Sent: Monday, February 13, 2017 10:32 PM >>>> >>>> hvm_hw_cpu->msr_flags is in fact the VMX dirty bitmap of MSRs needing to be >>>> restored when switching into guest context. It should never have been >>>> part of >>>> the migration state to start with, and Xen must not make any decisions >>>> based >>>> on the value seen during restore. >>>> >>>> Identify it as obsolete in the header files, consistently save it as zero >>>> and >>>> ignore it on restore. >>>> >>>> The MSRs must be considered dirty during VMCS creation to cause the proper >>>> defaults of 0 to be visible to the guest. >>>> >>>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> >>> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>, with one small comment. >>> >>> the effect of this patch should be more than not leaking syscall MSR. >>> what about making the subject clearer when check-in? >> What other effects do you think are going on here? Yes, we now context >> switch the MSRs right from the start of the domain, but that is >> necessary to avoid leaking them. >> > If just looking at this patch, it's for general MSR save/restore policy, > nothing specific to syscall MSR. The only three MSRs which use this infrastructure are LSTAR, STAR and FMASK. What if I were to clarify that in the first paragraph? ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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