diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2026-03-05 20:49:55 +0100 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2026-03-12 10:56:10 -0700 |
| commit | 2619da73bb2f10d88f7e1087125c40144fdf0987 (patch) | |
| tree | 0de0979fb7411831fc7b04da3a9d0288f30cde92 /include/uapi | |
| parent | d2ea4ff1ce50787a98a3900b3fb1636f3620b7cf (diff) | |
KVM: x86: Use __DECLARE_FLEX_ARRAY() for UAPI structures with VLAs
Commit 94dfc73e7cf4 ("treewide: uapi: Replace zero-length arrays with
flexible-array members") broke the userspace API for C++.
These structures ending in VLAs are typically a *header*, which can be
followed by an arbitrary number of entries. Userspace typically creates
a larger structure with some non-zero number of entries, for example in
QEMU's kvm_arch_get_supported_msr_feature():
struct {
struct kvm_msrs info;
struct kvm_msr_entry entries[1];
} msr_data = {};
While that works in C, it fails in C++ with an error like:
flexible array member 'kvm_msrs::entries' not at end of 'struct msr_data'
Fix this by using __DECLARE_FLEX_ARRAY() for the VLA, which uses [0]
for C++ compilation.
Fixes: 94dfc73e7cf4 ("treewide: uapi: Replace zero-length arrays with flexible-array members")
Cc: stable@vger.kernel.org
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://patch.msgid.link/3abaf6aefd6e5efeff3b860ac38421d9dec908db.camel@infradead.org
[sean: tag for stable@]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/linux/kvm.h | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 80364d4dbebb..3f0d8d3c3daf 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -11,6 +11,7 @@ #include <linux/const.h> #include <linux/types.h> #include <linux/compiler.h> +#include <linux/stddef.h> #include <linux/ioctl.h> #include <asm/kvm.h> @@ -542,7 +543,7 @@ struct kvm_coalesced_mmio { struct kvm_coalesced_mmio_ring { __u32 first, last; - struct kvm_coalesced_mmio coalesced_mmio[]; + __DECLARE_FLEX_ARRAY(struct kvm_coalesced_mmio, coalesced_mmio); }; #define KVM_COALESCED_MMIO_MAX \ @@ -592,7 +593,7 @@ struct kvm_clear_dirty_log { /* for KVM_SET_SIGNAL_MASK */ struct kvm_signal_mask { __u32 len; - __u8 sigset[]; + __DECLARE_FLEX_ARRAY(__u8, sigset); }; /* for KVM_TPR_ACCESS_REPORTING */ @@ -1051,7 +1052,7 @@ struct kvm_irq_routing_entry { struct kvm_irq_routing { __u32 nr; __u32 flags; - struct kvm_irq_routing_entry entries[]; + __DECLARE_FLEX_ARRAY(struct kvm_irq_routing_entry, entries); }; #define KVM_IRQFD_FLAG_DEASSIGN (1 << 0) @@ -1142,7 +1143,7 @@ struct kvm_dirty_tlb { struct kvm_reg_list { __u64 n; /* number of regs */ - __u64 reg[]; + __DECLARE_FLEX_ARRAY(__u64, reg); }; struct kvm_one_reg { @@ -1608,7 +1609,7 @@ struct kvm_stats_desc { #ifdef __KERNEL__ char name[KVM_STATS_NAME_SIZE]; #else - char name[]; + __DECLARE_FLEX_ARRAY(char, name); #endif }; |