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target/i386/kvm.c: Don't mark cpuid_data as QEMU_PACKED 

clang complains about taking the address of a packed
member of a struct:

target/i386/kvm.c:1245:27: warning: taking address of packed member 'cpuid' of class or structure '' may result in an unaligned pointer value [-Waddress-of-packed-member]
    c = cpuid_find_entry(&cpuid_data.cpuid, 1, 0);
                          ^~~~~~~~~~~~~~~~
target/i386/kvm.c:1297:31: warning: taking address of packed member 'cpuid' of class or structure '' may result in an unaligned pointer value [-Waddress-of-packed-member]
        c = cpuid_find_entry(&cpuid_data.cpuid, kvm_base, 0);
                              ^~~~~~~~~~~~~~~~

The kernel's definitions of struct kvm_cpuid2 and struct
kvm_cpuid_entry2 are carefully set up with padding fields
so that there is no between-struct padding anyway, so
the QEMU_PACKED annotation is unnecessary and might result
in the compiler generating worse code. Drop it, and instead
assert at build time that there is no stray padding.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20181210114654.31433-1-peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Peter Maydell 2018-12-10 11:46:54 +00:00 committed by Eduardo Habkost
parent 1c65775ffc
commit 9115bb1213
1 changed files with 9 additions and 1 deletions
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10
target/i386/kvm.c
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@ -864,7 +864,15 @@ int kvm_arch_init_vcpu(CPUState *cs)
struct {
struct kvm_cpuid2 cpuid;
struct kvm_cpuid_entry2 entries[KVM_MAX_CPUID_ENTRIES];
} QEMU_PACKED cpuid_data;
} cpuid_data;
/*
* The kernel defines these structs with padding fields so there
* should be no extra padding in our cpuid_data struct.
*/
QEMU_BUILD_BUG_ON(sizeof(cpuid_data) !=
sizeof(struct kvm_cpuid2) +
sizeof(struct kvm_cpuid_entry2) * KVM_MAX_CPUID_ENTRIES);
X86CPU *cpu = X86_CPU(cs);
CPUX86State *env = &cpu->env;
uint32_t limit, i, j, cpuid_i;