Re: [Qemu-devel] [PULL 07/28] x86/cpu: use standard-headers/asm-x86.kvm_para.h

[Peter Maydell <peter.maydell@linaro.org>]

On 25 May 2018 at 12:06, Peter Maydell <peter.maydell@linaro.org> wrote:
> On 23 May 2018 at 15:43, Michael S. Tsirkin <mst@redhat.com> wrote:
>> Switch to the header we imported from Linux,
>> this allows us to drop a hack in kvm_i386.h.
>> More code will be dropped in the next patch.
>>
>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>
>> --- a/target/i386/cpu.h
>> +++ b/target/i386/cpu.h
>> @@ -688,8 +688,6 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
>>  #define CPUID_7_0_EDX_SPEC_CTRL     (1U << 26) /* Speculation Control */
>>  #define CPUID_7_0_EDX_SPEC_CTRL_SSBD  (1U << 31) /* Speculative Store Bypass Disable */
>>
>> -#define KVM_HINTS_DEDICATED (1U << 0)
>> -
>>  #define CPUID_8000_0008_EBX_IBPB    (1U << 12) /* Indirect Branch Prediction Barrier */
>>
>>  #define CPUID_XSAVE_XSAVEOPT   (1U << 0)
>
> Hi -- this seems like it will break compilation when we next
> update our copy of the Linux kernel headers, because (as of
> 4.17-rc6, at least), asm-x86/kvm_para.h doesn't define
> KVM_HINTS_DEDICATED.

For the moment I'm using this workaround (I wanted to do a header
update for something else I'm working on):

--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -48,6 +48,11 @@
 #include "exec/memattrs.h"
 #include "trace.h"

+/* Work around this kernel header constant changing its name */
+#ifndef KVM_HINTS_REALTIME
+#define KVM_HINTS_REALTIME KVM_HINTS_DEDICATED
+#endif
+
 //#define DEBUG_KVM

 #ifdef DEBUG_KVM
@@ -387,7 +392,7 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s,
uint32_t function,
             ret &= ~(1U << KVM_FEATURE_PV_UNHALT);
         }
     } else if (function == KVM_CPUID_FEATURES && reg == R_EDX) {
-        ret |= 1U << KVM_HINTS_DEDICATED;
+        ret |= 1U << KVM_HINTS_REALTIME;
         found = 1;
     }

thanks
-- PMM