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Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Borislav Petkov , Michael Roth , Vlastimil Babka , tony.luck@intel.com, Nathaniel McCallum , brijesh.ksingh@gmail.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9160E1003ECC X-Stat-Signature: ztwiwdsycy771mwkrarsgqppz96yg9ti Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=google.com header.s=20161025 header.b=s5pTurZ1; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf07.hostedemail.com: domain of pgonda@google.com designates 209.85.167.48 as permitted sender) smtp.mailfrom=pgonda@google.com X-HE-Tag: 1626115477-166212 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > +int psmash(struct page *page) > +{ > + unsigned long spa = page_to_pfn(page) << PAGE_SHIFT; > + int ret; > + > + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) > + return -ENXIO; > + > + /* Retry if another processor is modifying the RMP entry. */ > + do { > + /* Binutils version 2.36 supports the PSMASH mnemonic. */ > + asm volatile(".byte 0xF3, 0x0F, 0x01, 0xFF" > + : "=a"(ret) > + : "a"(spa) > + : "memory", "cc"); > + } while (ret == FAIL_INUSE); Should there be some retry limit here for safety? Or do we know that we'll never be stuck in this loop? Ditto for the loop in rmpupdate. > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(psmash); >