Messages in this thread | | | Date | Mon, 18 Oct 2021 13:44:30 +0200 | Subject | Re: [PATCH RFC] KVM: SVM: reduce guest MAXPHYADDR by one in case C-bit is a physical bit | From | Paolo Bonzini <> |
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On 17/10/21 09:54, Maxim Levitsky wrote: > > I'll say, a hack to reduce it by 1 bit is still better that failing > tests, at least until AMD explains to us, about what is going on.
What's going on is documented in the thread at https://yhbt.net/lore/all/4f46f3ab-60e4-3118-1438-10a1e17cd900@suse.com/:
> That doesn't really follow what Andrew gave us, namely: > > 1) On parts with <40 bits, its fully hidden from software > > 2) Before Fam17h, it was always 12G just below 1T, even if there was > more RAM above this location > > 3) On Fam17h and later, it is variable based on SME, and is either > just below 2^48 (no encryption) or 2^43 (encryption)
If you can use this information to implement the fix, that'd be very nice. I didn't apply the hackish fix because I wanted to test it on a SME-enabled box.
Paolo
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