iqembu iAbacwaningi abavela eGraz University of Technology (Austria), eyayaziwa ngokuthuthukisa ukuhlasela kwe-MDS, NetSpectre, Throwhammer kanye neZombieLoad, uveze ukuhlasela kwesiteshi eseceleni okusha (CVE-2021-46778) kumugqa womprosesa we-AMD osetshenziselwa ukuhlela ukukhishwa kwemiyalo kumayunithi ahlukene okwenziwa e-CPU.
Ukuhlasela, kubizwe I-SQUIP, ivumela ukunquma idatha esetshenziswe ezibalweni kwenye inqubo noma umshini we-virtual noma uhlele ishaneli yokuxhumana efihliwe phakathi kwezinqubo noma imishini ebonakalayo evumela ukuthi idatha ishintshwe ngaphandle kokudlula ezindleleni zokulawula ukufinyelela kwesistimu.
I-Las Ama-CPU e-AMD asekelwe kuma-microarchitecture we-Zen woku-1, wesi-2 nowesithathu isizukulwane (AMD Ryzen 2000-5000, AMD Ryzen Threadripper, AMD Athlon 3000, AMD EPYC) Ingabe bayathinteka lapho kusetshenziswa ubuchwepheshe be-Simultaneous Multithreading (SMT) .
Ama-CPU esimanje asebenzisa idizayini eyi-superscalar, lapho imiyalo eminingi isetshenziswa kanyekanye ukuze kukhuliswe ukusebenza. Lawa ma-CPU acubungula imiyalelo ngendlela ehamba phambili ngezigaba ezimbalwa: (1) ukulanda, (2) khipha ikhodi, (3) uhlelo/ukhiphe, kanye (4) nokulanda.
Ukuhlasela kusekelwe ekuhloleni izinga lokuvela kombango (izinga lombango) emigqeni ehlukene yabahleli futhi kwenziwa ngesilinganiso sokubambezeleka lapho kuqaliswa ukuhlola okwenziwa kolunye uchungechunge lwe-SMT ku-CPU efanayo ebonakalayo. Ukuze kuhlaziywe okuqukethwe, kusetshenziswe indlela ye-Prime+Probe, ehlanganisa ukugcwalisa umugqa ngesethi yamanani ereferensi nokunquma izinguquko ngokulinganisa isikhathi sokufinyelela kuzo ngesikhathi sokulayisha kabusha.
Uhlelo/isiteji sokwenza singacubungula imiyalelo ngaphandle kwe-oda ukuze kukhuliswe ukufana kwezinga lemfundo. Sichaza kafushane ngasinye salezi zigaba:
-Sesha. I-CPU ibheka umyalo olandelayo ozowusebenzisa kunqolobane ye-L1i.
- Qopha. Ukuze kuvunyelwe ukusebenza kahle, imiyalelo etholiwe (imisebenzi emikhulu) ihlukaniswa ibe umshini omncane owodwa noma ngaphezulu (µops) futhi ibekwe kulayini we-µop. Lawa ma-µops afakwa ngemuva, lapho ahlelwa khona futhi asetshenziswa.
-Sheduli/Run. I(aba)shejuli balandelela ukuthi yimaphi ama-µops alungele ukusetshenziswa (anokungenayo okutholakalayo) futhi ahlele ngokushintshayo (ngaphandle kwe-oda) kumayunithi okusebenza atholakalayo. I-CPU core inamayunithi okubulala amaningi futhi ingaba namayunithi amaningi e-arithmetic and logic (ALUs), amayunithi e-branch execution (BRUs), amayunithi okukhiqiza ikheli (AGUs).
Ngesikhathi sokuhlolwa, abacwaningi bakwazile ukudala kabusha ngokuphelele ukhiye we-RSA oyimfihlo ongu-4096-bit isetshenziselwa ukudala amasiginesha edijithali kusetshenziswa ilabhulali ye-cryptography ye-mbedTLS 3.0, esebenzisa i-algorithm ye-Montgomery ukuphakamisa inombolo ibe yimoduli yamandla. Kudingeka imikhondo engu-50.500 ukuze kutholakale ukhiye.
Isikhathi esiphelele sokuhlasela sithathe imizuzu engama-38. Izinhlobonhlobo zokuhlasela ezinikeza ukuvuza phakathi kwezinqubo ezihlukene nemishini ebonakalayo elawulwa yi-KVM hypervisor iyaboniswa. Kuboniswa futhi ukuthi indlela ingasetshenziswa ukuhlela ukudluliswa kwedatha eyimfihlo phakathi kwemishini ebonakalayo ngenani elingu-0,89 Mbit/s naphakathi kwezinqubo ngesilinganiso esingu-2,70 Mbit/s ngenani lephutha elingaphansi kuka-0,8, XNUMX%.
I-CPU core ihlukaniswe yaba ama-logical cores amaningi, noma imicu, esebenzisa ukusakazwa kweziyalezo ezizimele kodwa ukwabelana ngezinsiza ezifana ne-L1i cache. Ama-µops alolu chungechunge aphinda abelane ngamayunithi okusebenzisa ukuze avumele ukusetshenziswa okuphezulu okuphezulu. Ukuhlukaniswa kwezingxenye ezihlukene ze-kernel.
Kwenziwa ngokushintshisana ngokuncintisana. Izakhiwo ze-AMD Zen zivumela imicu emibili
ngomongo ngamunye. Lezi zintambo zingasuka ohlelweni olulodwa noma ezinhlelweni ezihlukene, njengoba ziphethwe isistimu yokusebenza.
Ama-Intel processors awathinteki kalula ukuhlasela ngoba zisebenzisa ulayini wokuhlela owodwa, kuyilapho amaphrosesa e-AMD asengozini esebenzisa imigqa ehlukene yeyunithi ngayinye yokwenza.
Njengesixazululo sokuvimba ukuvuza kolwazi, I-AMD iyanconywa labo bathuthukisi sebenzisa ama-algorithms ahlala enza izibalo zezibalo ngesikhathi esifanayo, ngokunganaki imvelo yedatha ecutshungulwayo, futhi ivimbela ukufokhwa okusekelwe kudatha eyimfihlo.
Okokugcina, uma ungathanda ukwazi okwengeziwe ngakho, ungathintana nemininingwane ku isixhumanisi esilandelayo.