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Peter Anvin" , Ashish Kalra , John Allen , Herbert Xu , "David S. Miller" , Ard Biesheuvel , Neeraj Upadhyay , Kishon Vijay Abraham I , Alexey Kardashevskiy , Nikunj A Dadhania , "Peter Zijlstra (Intel)" , Kim Phillips , Sean Christopherson Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org References: <20260407174713.439474-1-tycho@kernel.org> <20260407174713.439474-2-tycho@kernel.org> From: Tom Lendacky Content-Language: en-US Autocrypt: addr=thomas.lendacky@amd.com; keydata= xsFNBFaNZYkBEADxg5OW/ajpUG7zgnUQPsMqWPjeAxtu4YH3lCUjWWcbUgc2qDGAijsLTFv1 kEbaJdblwYs28z3chM7QkfCGMSM29JWR1fSwPH18WyAA84YtxfPD8bfb1Exwo0CRw1RLRScn 6aJhsZJFLKyVeaPO1eequEsFQurRhLyAfgaH9iazmOVZZmxsGiNRJkQv4YnM2rZYi+4vWnxN 1ebHf4S1puN0xzQsULhG3rUyV2uIsqBFtlxZ8/r9MwOJ2mvyTXHzHdJBViOalZAUo7VFt3Fb aNkR5OR65eTL0ViQiRgFfPDBgkFCSlaxZvc7qSOcrhol160bK87qn0SbYLfplwiXZY/b/+ez 0zBtIt+uhZJ38HnOLWdda/8kuLX3qhGL5aNz1AeqcE5TW4D8v9ndYeAXFhQI7kbOhr0ruUpA udREH98EmVJsADuq0RBcIEkojnme4wVDoFt1EG93YOnqMuif76YGEl3iv9tYcESEeLNruDN6 LDbE8blkR3151tdg8IkgREJ+dK+q0p9UsGfdd+H7pni6Jjcxz8mjKCx6wAuzvArA0Ciq+Scg hfIgoiYQegZjh2vF2lCUzWWatXJoy7IzeAB5LDl/E9vz72cVD8CwQZoEx4PCsHslVpW6A/6U NRAz6ShU77jkoYoI4hoGC7qZcwy84mmJqRygFnb8dOjHI1KxqQARAQABzSZUb20gTGVuZGFj a3kgPHRob21hcy5sZW5kYWNreUBhbWQuY29tPsLBmQQTAQoAQwIbIwcLCQgHAwIBBhUIAgkK CwQWAgMBAh4BAheAAhkBFiEE3Vil58OMFCw3iBv13v+a5E8wTVMFAmkbaKgFCRZQah8ACgkQ 3v+a5E8wTVPFyg//UYANiuHfxxJET8D6p/vIV0xYcf1SXCG78M+5amqcE/4cCIJWyAT3A1nP zwyQIaIjUlGsXQtNgC1uVteCnMNJCjVQm0nLlJ9IVtXxzRg0QKjuSdZxuL5jrIon4xW9hTJR 94i2v3Fx5UWyP2TB6qZOcB0jgh0l01GHF9/DVJbmQlpvQB4Z1uNv09Q7En6EXi28TSv0Ffd1 p8vKqxwz7CMeAeZpn5i7s1QE/mQtdkyAmhuGD12tNbWzFamrDD1Kq3Em4TIFko0+k5+oQAAf JFaZc1c0D4GtXwvv4y+ssI0eZuOBXapUHeNNVf3JGuF6ZPLNPAe5gMQrmsJinEArVYRQCuDA BZakbKw9YJpGhnSVeCl2zSHcVgXuDs4J2ONxdsGynYv5cjPb4XTYPaE1CZH7Vy1tqma8eErG rcCyP1seloaC1UQcp8UDAyEaBjh3EqvTvgl+SppHz3im0gPJgR9km95BA8iGx9zqDuceATBc +A007+XxdFIsifMGlus0DKPmNAJaLkEEUMedBBxH3bwQ+z8tmWHisCZQJpUeGkwttD1LK/xn KRnu8AQpSJBB2oKAX1VtLRn8zLQdGmshxvsLUkKdrNE6NddhhfULqufNBqul0rrHGDdKdTLr cK5o2dsf9WlC4dHU2PiXP7RCjs1E5Ke0ycShDbDY5Zeep/yhNWLOwU0EVo1liQEQAL7ybY01 hvEg6pOh2G1Q+/ZWmyii8xhQ0sPjvEXWb5MWvIh7RxD9V5Zv144EtbIABtR0Tws7xDObe7bb r9nlSxZPur+JDsFmtywgkd778G0nDt3i7szqzcQPOcR03U7XPDTBJXDpNwVV+L8xvx5gsr2I bhiBQd9iX8kap5k3I6wfBSZm1ZgWGQb2mbiuqODPzfzNdKr/MCtxWEsWOAf/ClFcyr+c/Eh2 +gXgC5Keh2ZIb/xO+1CrTC3Sg9l9Hs5DG3CplCbVKWmaL1y7mdCiSt2b/dXE0K1nJR9ZyRGO lfwZw1aFPHT+Ay5p6rZGzadvu7ypBoTwp62R1o456js7CyIg81O61ojiDXLUGxZN/BEYNDC9 n9q1PyfMrD42LtvOP6ZRtBeSPEH5G/5pIt4FVit0Y4wTrpG7mjBM06kHd6V+pflB8GRxTq5M 7mzLFjILUl9/BJjzYBzesspbeoT/G7e5JqbiLWXFYOeg6XJ/iOCMLdd9RL46JXYJsBZnjZD8 Rn6KVO7pqs5J9K/nJDVyCdf8JnYD5Rq6OOmgP/zDnbSUSOZWrHQWQ8v3Ef665jpoXNq+Zyob pfbeihuWfBhprWUk0P/m+cnR2qeE4yXYl4qCcWAkRyGRu2zgIwXAOXCHTqy9TW10LGq1+04+ LmJHwpAABSLtr7Jgh4erWXi9mFoRABEBAAHCwXwEGAEKACYCGwwWIQTdWKXnw4wULDeIG/Xe /5rkTzBNUwUCaRto5wUJFlBqXgAKCRDe/5rkTzBNUw4/EAClG106SeHXiJ+ka6aeHysDNVgZ 8pUbB2f8dWI7kzD5AZ5kLENnsi1MzJRYBwtg/vVVorZh6tavUwcIvsao+TnV57gXAWr6sKIc xyipxRVEXmHts22I6vL1DirLAoOLAwWilkM+JzbVE3MMvC+cCVnMzzchrMYDTqn1mjCCwiIe u5oop+K/RgeHYPsraumyA9/kj8iazrLM+lORukCNM7+wlRClcY8TGX+VllANym9B6FMxsJ5z Q7JeeXIgyGlcBRME+m3g40HfIl+zM674gjv2Lk+KjS759KlX27mQfgnAPX4tnjLcmpSQJ77I Qg+Azi/Qloiw7L/WsmxEO5ureFgGIYDQQUeM1Qnk76K5Z3Nm8MLHtjw3Q7kXHrbYn7tfWh4B 7w5Lwh6NoF88AGpUrosARVvIAd93oo0B9p40Or4c5Jao1qqsmmCCD0dl7WTJCboYTa2OWd99 oxS7ujw2t1WMPD0cmriyeaFZnT5cjGbhkA+uQGuT0dMQJdLqW3HRwWxyiGU/jZUFjHGFmUrj qFAgP+x+ODm6/SYn0LE0VLbYuEGfyx5XcdNnSvww1NLUxSvuShcJMII0bSgP3+KJtFqrUx9z l+/NCGvn/wMy6NpYUpRSOmsqVv0N71LbtXnHRrJ42LzWiRW2I5IWsb1TfdMAyVToHPNaEb0i WiyqywZI5g== In-Reply-To: <20260407174713.439474-2-tycho@kernel.org> Content-Type: text/plain; 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If there are some CPUs > offline, they will not run the setup functions, so SNP initialization will > always fail. > > Skip the IPIs in this case and return an error so that the CCP driver can > skip the SNP_INIT that will fail. Also print the CPU masks as a breadcrumb > so people can figure out what happened. > > Suggested-by: Borislav Petkov (AMD) > Signed-off-by: Tycho Andersen (AMD) > --- > arch/x86/include/asm/sev.h | 4 ++-- > arch/x86/virt/svm/sev.c | 15 +++++++++++++-- > 2 files changed, 15 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index 09e605c85de4..594cfa19cbd4 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -661,7 +661,7 @@ static inline void snp_leak_pages(u64 pfn, unsigned int pages) > { > __snp_leak_pages(pfn, pages, true); > } > -void snp_prepare(void); > +int snp_prepare(void); > void snp_shutdown(void); > #else > static inline bool snp_probe_rmptable_info(void) { return false; } > @@ -679,7 +679,7 @@ static inline void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp) > static inline void snp_leak_pages(u64 pfn, unsigned int npages) {} > static inline void kdump_sev_callback(void) { } > static inline void snp_fixup_e820_tables(void) {} > -static inline void snp_prepare(void) {} > +static inline int snp_prepare(void) { return -ENODEV; } > static inline void snp_shutdown(void) {} > #endif > > diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c > index 41f76f15caa1..160e60f5f3fb 100644 > --- a/arch/x86/virt/svm/sev.c > +++ b/arch/x86/virt/svm/sev.c > @@ -511,8 +511,9 @@ static void clear_hsave_pa(void *arg) > wrmsrq(MSR_VM_HSAVE_PA, 0); > } > > -void snp_prepare(void) > +int snp_prepare(void) > { > + int ret = -EOPNOTSUPP; I prefer seeing the return value set in the error condition, but that's just my preference. > u64 val; > > /* > @@ -521,12 +522,19 @@ void snp_prepare(void) > */ > rdmsrq(MSR_AMD64_SYSCFG, val); > if (val & MSR_AMD64_SYSCFG_SNP_EN) > - return; > + return 0; > > clear_rmp(); > > cpus_read_lock(); > > + if (!cpumask_equal(cpu_online_mask, cpu_present_mask)) { > + pr_warn("Skipping SNP initialization. CPUs online %*pbl, present %*pbl\n", > + cpumask_pr_args(cpu_online_mask), > + cpumask_pr_args(cpu_present_mask)); > + goto unlock; > + } > + > /* > * MtrrFixDramModEn is not shared between threads on a core, > * therefore it must be set on all CPUs prior to enabling SNP. > @@ -537,7 +545,10 @@ void snp_prepare(void) > /* SNP_INIT requires MSR_VM_HSAVE_PA to be cleared on all CPUs. */ > on_each_cpu(clear_hsave_pa, NULL, 1); > > + ret = 0; I would also prefer a blank line here... > +unlock: > cpus_read_unlock(); and here. But, again, that's just me. If you don't need another version, that's not enough to redo it. Reviewed-by: Tom Lendacky > + return ret; > } > EXPORT_SYMBOL_FOR_MODULES(snp_prepare, "ccp"); >