On 30/04/2024 1:45 pm, Jan Beulich wrote: > On 29.04.2024 17:16, Andrew Cooper wrote: >> Allocate two new feature leaves, and extend cpu_policy with the non-feature >> fields too. >> >> The CPUID dependency between the SVM bit on the whole SVM leaf is >> intentionally deferred, to avoid transiently breaking nested virt. > In reply to this I meant to ask that you at least add those dependencies in > commented-out form, such that from looking at gen-cpuid.py it becomes clear > they're intentionally omitted. But you don't add feature identifiers either, > making dependencies impossible to express. Maybe this sentence was really > meant for another of the patches? (Then my request would actually apply > there.)
This is necessary because c/s 4f8b0e94d7ca is buggy. Notice how it puts an edit to the policy object in the middle of a block of logic editing the featureset, which ends with writing the featureset back over the policy object. And it's not the first outstanding problem from what is a very small number of nested-virt patches so far... >> @@ -296,7 +298,16 @@ struct cpu_policy >> uint32_t /* d */:32; >> >> uint64_t :64, :64; /* Leaf 0x80000009. */ >> - uint64_t :64, :64; /* Leaf 0x8000000a - SVM rev and features. */ >> + >> + /* Leaf 0x8000000a - SVM rev and features. */ >> + uint8_t svm_rev, :8, :8, :8; >> + uint32_t /* b */ :32; >> + uint32_t nr_asids; > According to the doc I'm looking at it is %ebx which holds the number of > ASIDs and %ecx is reserved. With that adjusted That's fun... The PPR I used for this has it wrong. A sample of others match the APM, so I'll raise a bug with AMD against this PPR. > Reviewed-by: Jan Beulich <jbeul...@suse.com> Thanks. ~Andrew
