[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2/3] libx86: introduce a helper to deserialise msr_policy objects
From: Roger Pau Monné <roger.pau@xxxxxxxxxx> Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> --- CC: Jan Beulich <JBeulich@xxxxxxxx> CC: Wei Liu <wei.liu2@xxxxxxxxxx> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx> CC: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx> --- xen/include/xen/lib/x86/msr.h | 21 ++++++++++++++ xen/lib/x86/msr.c | 67 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 88 insertions(+) diff --git a/xen/include/xen/lib/x86/msr.h b/xen/include/xen/lib/x86/msr.h index e2cfbb1..6236622 100644 --- a/xen/include/xen/lib/x86/msr.h +++ b/xen/include/xen/lib/x86/msr.h @@ -48,6 +48,27 @@ typedef xen_msr_entry_t msr_entry_buffer_t[]; int x86_msr_copy_to_buffer(const struct msr_policy *policy, msr_entry_buffer_t msrs, uint32_t *nr_entries); +/** + * Unserialise an msr_policy object from an array of msrs. + * + * @param policy The msr_policy object to unserialise into. + * @param msrs The array of msrs to unserialise from. + * @param nr_entries The number of entries in 'msrs'. + * @param err_msr Optional hint filled on error. + * @returns -errno + * + * Reads at most MSR_MAX_SERIALISED_ENTRIES. May fail for a number of reasons + * based on the content in an individual 'msrs' entry, including the MSR index + * not being valid in the policy, the flags field being nonzero, or if the + * value provided would truncate when stored in the policy. In such cases, + * the optional err_* pointer is filled in to aid diagnostics. + * + * No content validation is performed on the data stored in the policy object. + */ +int x86_msr_copy_from_buffer(struct msr_policy *policy, + const msr_entry_buffer_t msrs, uint32_t nr_entries, + uint32_t *err_msr); + #endif /* !XEN_LIB_X86_MSR_H */ /* diff --git a/xen/lib/x86/msr.c b/xen/lib/x86/msr.c index 60fb567..e498124 100644 --- a/xen/lib/x86/msr.c +++ b/xen/lib/x86/msr.c @@ -47,6 +47,73 @@ int x86_msr_copy_to_buffer(const struct msr_policy *p, return 0; } +int x86_msr_copy_from_buffer(struct msr_policy *p, + const msr_entry_buffer_t msrs, uint32_t nr_entries, + uint32_t *err_msr) +{ + unsigned int i; + xen_msr_entry_t data; + int rc; + + /* + * A well formed caller is expected pass an array with entries in order, + * and without any repetitions. However, due to per-vendor differences, + * and in the case of upgrade or levelled scenarios, we typically expect + * fewer than MAX entries to be passed. + * + * Detecting repeated entries is prohibitively complicated, so we don't + * bother. That said, one way or another if more than MAX entries are + * passed, something is wrong. + */ + if ( nr_entries > MSR_MAX_SERIALISED_ENTRIES ) + return -E2BIG; + + for ( i = 0; i < nr_entries; i++ ) + { + if ( copy_from_buffer_offset(&data, msrs, i, 1) ) + return -EFAULT; + + if ( data.flags ) /* .flags MBZ */ + { + rc = -EINVAL; + goto err; + } + + switch ( data.idx ) + { + /* + * Assign data.val to 'field', checking for truncation if the + * backing storage for 'field' is smaller than uint64_t + */ +#define ASSIGN(field) \ +({ \ + if ( (typeof(field))data.val != data.val ) \ + { \ + rc = -EOVERFLOW; \ + goto err; \ + } \ + field = data.val; \ +}) + + case MSR_INTEL_PLATFORM_INFO: ASSIGN(p->plaform_info.raw); break; + +#undef ASSIGN + + default: + rc = -ERANGE; + goto err; + } + } + + return 0; + + err: + if ( err_msr ) + *err_msr = data.idx; + + return rc; +} + /* * Local variables: * mode: C -- 2.1.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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