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Date: Wed, 25 Mar 2020 16:46:58 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: Randy Dunlap <rdunlap@...radead.org>,
Stephen Rothwell <sfr@...b.auug.org.au>,
Linux Next Mailing List <linux-next@...r.kernel.org>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
KVM <kvm@...r.kernel.org>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>
Subject: Re: linux-next: Tree for Mar 25 (arch/x86/kvm/)
On 25/03/20 16:30, Randy Dunlap wrote:
> 24 (only showing one of them here) BUILD_BUG() errors in arch/x86/kvm/cpuid.h
> function __cpuid_entry_get_reg(), for the default: case.
>
>
> CC arch/x86/kvm/cpuid.o
> In file included from ../include/linux/export.h:43:0,
> from ../include/linux/linkage.h:7,
> from ../include/linux/preempt.h:10,
> from ../include/linux/hardirq.h:5,
> from ../include/linux/kvm_host.h:7,
> from ../arch/x86/kvm/cpuid.c:12:
> In function ‘__cpuid_entry_get_reg’,
> inlined from ‘kvm_cpu_cap_mask’ at ../arch/x86/kvm/cpuid.c:272:25,
> inlined from ‘kvm_set_cpu_caps’ at ../arch/x86/kvm/cpuid.c:292:2:
> ../include/linux/compiler.h:394:38: error: call to ‘__compiletime_assert_114’ declared with attribute error: BUILD_BUG failed
> _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
> ^
> ../include/linux/compiler.h:375:4: note: in definition of macro ‘__compiletime_assert’
> prefix ## suffix(); \
> ^~~~~~
> ../include/linux/compiler.h:394:2: note: in expansion of macro ‘_compiletime_assert’
> _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
> ^~~~~~~~~~~~~~~~~~~
> ../include/linux/build_bug.h:39:37: note: in expansion of macro ‘compiletime_assert’
> #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
> ^~~~~~~~~~~~~~~~~~
> ../include/linux/build_bug.h:59:21: note: in expansion of macro ‘BUILD_BUG_ON_MSG’
> #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
> ^~~~~~~~~~~~~~~~
> ../arch/x86/kvm/cpuid.h:114:3: note: in expansion of macro ‘BUILD_BUG’
> BUILD_BUG();
> ^~~~~~~~~
>
Looks like the compiler is not smart enough to figure out the constant
expressions in BUILD_BUG. I think we need to do something like this:
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 23b4cd1ad986..8f711b0cdec0 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -40,6 +40,7 @@ struct cpuid_reg {
int reg;
};
+/* Update reverse_cpuid_check as well when adding an entry. */
static const struct cpuid_reg reverse_cpuid[] = {
[CPUID_1_EDX] = { 1, 0, CPUID_EDX},
[CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX},
@@ -68,12 +69,21 @@ static const struct cpuid_reg reverse_cpuid[] = {
*/
static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
{
- BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
- BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
- BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
- BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
- BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
- BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
+ BUILD_BUG_ON(x86_leaf != CPUID_1_EDX &&
+ x86_leaf != CPUID_8000_0001_EDX &&
+ x86_leaf != CPUID_8086_0001_EDX &&
+ x86_leaf != CPUID_1_ECX &&
+ x86_leaf != CPUID_C000_0001_EDX &&
+ x86_leaf != CPUID_8000_0001_ECX &&
+ x86_leaf != CPUID_7_0_EBX &&
+ x86_leaf != CPUID_D_1_EAX &&
+ x86_leaf != CPUID_8000_0008_EBX &&
+ x86_leaf != CPUID_6_EAX &&
+ x86_leaf != CPUID_8000_000A_EDX &&
+ x86_leaf != CPUID_7_ECX &&
+ x86_leaf != CPUID_8000_0007_EBX &&
+ x86_leaf != CPUID_7_EDX &&
+ x86_leaf != CPUID_7_1_EAX);
}
/*
Randy, can you test it with your compiler?
Thanks,
Paolo
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