Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: - [High] arm64: hyperv: kcalloc does not guarantee 256-byte alignment for rsi_host_call - [Low] arm64: hyperv: unnecessary early boot memory allocation error handling --
commit ef58d4d121fbefca0e2e24ac57c717abd6fc93ba Author: Kameron Carr <[email protected]> arm64: hyperv: Add per-CPU RSI host call infrastructure for CCA Realms This commit allocates a per-CPU array of rsi_host_call structures in hyperv_init() for Realm guests. The array is used to route hypercalls through the RSI_HOST_CALL interface since Arm CCA Realms cannot issue Hyper-V hypercalls via HVC. > diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c > index 4fdc26ade1d74..b1657cfabd7d1 100644 > --- a/arch/arm64/hyperv/mshyperv.c > +++ b/arch/arm64/hyperv/mshyperv.c [ ... ] > @@ -85,6 +90,20 @@ static int __init hyperv_init(void) > if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc()) > return 0; > > + /* > + * The RSI host-call buffers are only ever used when > + * is_realm_world() is true. Skip the allocation on non-Realm > + * guests. A single contiguous array of nr_cpu_ids entries is > + * allocated; each CPU indexes into it by its processor ID. > + */ > + if (is_realm_world()) { > + hv_hostcall_array = kcalloc(nr_cpu_ids, > + sizeof(struct rsi_host_call), > + GFP_KERNEL); [Severity: High] Does kcalloc guarantee the 256-byte alignment required by the RMM ABI for the RSI_HOST_CALL structure? When hv_do_rsi_hypercall() passes virt_to_phys(&hv_hostcall_array[smp_processor_id()]) to rsi_host_call(), the RMM might reject the hypercall if the physical address is unaligned, which would break Realm guest booting. The kcalloc API only guarantees ARCH_KMALLOC_MINALIGN (e.g., 8 or 16 bytes) and does not respect the __aligned(256) attribute of the type. Furthermore, when CONFIG_SLUB_DEBUG is enabled, redzones will shift the object pointer away from natural alignment, ensuring that the 256-byte alignment requirement is violated. > + if (!hv_hostcall_array) > + return -ENOMEM; [Severity: Low] Is returning -ENOMEM here necessary? Because hyperv_init() is executed via early_initcall, physical memory should be available. Complex error handling, cleanup logic, or returning -ENOMEM in these early boot functions is often unnecessary dead code, as an allocation failure typically means the system cannot boot anyway. > + } > > /* Setup the guest ID */ > guest_id = hv_generate_guest_id(LINUX_VERSION_CODE); [ ... ] > @@ -125,6 +144,11 @@ static int __init hyperv_init(void) > > hyperv_initialized = true; > return 0; > + > +free_hostcall_mem: > + kfree(hv_hostcall_array); > + hv_hostcall_array = NULL; > + return ret; [Severity: Low] Can we omit this explicit cleanup path? As noted above, executing cleanup logic for failures that are fatal during early boot adds unnecessary code complexity. > } > > early_initcall(hyperv_init); -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=3
