[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH][SVM] Fix 32bit Windows guest VMs save/restore
On 31/01/2011 22:13, "Keir Fraser" <keir@xxxxxxx> wrote: > This handling of the SYSENTER MSRs is overly complicated. By the way, apart from the complexity, I suspect the current approach has further bugs because I don't believe the canonical sysenter msr values are correctly shuffled between the vmcb and vcpu structures when a guest moves in and out of long mode. Just another example why having two different canonical places for one data item is a bad idea. -- Keir > I suggest > reverting a bunch of the original handling of cross-vendor migration as > follows: > * Never intercept the SYSENTER MSRs. > * Remove the vcpu->arch.hvm_svm.guest_sysenter_* fields. > * Always hvm save/restore from/to the values in the vmcb. > * Modify svm_msr_read_intercept(MSR_IA32_SYSENTER_*) to svm_sync_vmcb() and > then read the sysenter msr value from vmcb > * Modify svm_msr_write_intercept(MSR_IA32_SYSENTER_*) to svm_sync_vmcb(), > then modify the sysenter msr in the vmcb, and then svm_vmload(). > > Result is that we get rid of some redundant fields from the vcpu structure > and have one canonical place we always keep the sysenter msr values, in the > vmcb. The extra cost in the msr read/write functions is totally > inconsequential, and only used after guest migration from an Intel CPU > anyway. Hardly something to optimise for. > > -- Keir > >> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@xxxxxxxxxxxxxxxxxxx >> http://lists.xensource.com/xen-devel > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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