Re: [Qemu-devel] [PATCH] Resend - Added x86/tsc_adjust.c to test the ia32_tsc_adjust funtionality.

[Marcelo Tosatti]

Will,

1. Please check CPUID before using ADJUST_TSC MSR, exit test successfully
if CPUID bit disabled.

2. Please test the implementation of ADJUST_TSC MSR (functional test). 
vmexit.flat test can be used for performance of MSR emulation.

Example

        tsc1 = rdtsc();
        wrmsr(IA32_TSC_ADJUST, 100000000000ull);
        tsc2 = rdtsc();
        if (tsc2 - tsc1 < 100000000000ull) {
                printf("failure ... should be ...");
                failure++;
        }
        ...
        write to tsc
        check if IA32_TSC_ADJUST is adjusted accordingly

        return !failure ? 0 : 1;

Thanks

On Mon, Nov 26, 2012 at 10:44:14AM -0800, Will Auld wrote:
> Signed-off-by: Will Auld <address@hidden>
> ---
>  config-x86-common.mak |  5 ++++-
>  x86/tsc_adjust.c      | 43 +++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 47 insertions(+), 1 deletion(-)
>  create mode 100644 x86/tsc_adjust.c
> 
> diff --git a/config-x86-common.mak b/config-x86-common.mak
> index c76cd11..47a9056 100644
> --- a/config-x86-common.mak
> +++ b/config-x86-common.mak
> @@ -34,7 +34,8 @@ tests-common = $(TEST_DIR)/vmexit.flat $(TEST_DIR)/tsc.flat 
> \
>                 $(TEST_DIR)/realmode.flat $(TEST_DIR)/msr.flat \
>                 $(TEST_DIR)/hypercall.flat $(TEST_DIR)/sieve.flat \
>                 $(TEST_DIR)/kvmclock_test.flat  $(TEST_DIR)/eventinj.flat \
> -               $(TEST_DIR)/s3.flat $(TEST_DIR)/pmu.flat 
> $(TEST_DIR)/asyncpf.flat
> +               $(TEST_DIR)/s3.flat $(TEST_DIR)/pmu.flat \
> +            $(TEST_DIR)/tsc_adjust.flat $(TEST_DIR)/asyncpf.flat
>  
>  ifdef API
>  tests-common += api/api-sample
> @@ -64,6 +65,8 @@ $(TEST_DIR)/port80.elf: $(cstart.o) $(TEST_DIR)/port80.o
>  
>  $(TEST_DIR)/tsc.elf: $(cstart.o) $(TEST_DIR)/tsc.o
>  
> +$(TEST_DIR)/tsc_adjust.elf: $(cstart.o) $(TEST_DIR)/tsc_adjust.o
> +
>  $(TEST_DIR)/apic.elf: $(cstart.o) $(TEST_DIR)/apic.o
>  
>  $(TEST_DIR)/realmode.elf: $(TEST_DIR)/realmode.o
> diff --git a/x86/tsc_adjust.c b/x86/tsc_adjust.c
> new file mode 100644
> index 0000000..bcb8982
> --- /dev/null
> +++ b/x86/tsc_adjust.c
> @@ -0,0 +1,43 @@
> +#include "libcflat.h"
> +#include "processor.h"
> +
> +#define IA32_TSC_ADJUST 0x3b
> +
> +int main()
> +{
> +     u64 t1, t2, t3, t4, t5;
> +     u64 lat;
> +
> +     t3 = 0x0;
> +
> +     t1 = rdtsc();
> +     wrmsr(IA32_TSC_ADJUST, t3);
> +     t2 = rdtsc();
> +     lat = t2 - t1;
> +     printf("rdtsc/wrmsr/rdtsc latency %lld\n", lat);
> +     printf("Initial rdtsc: %lld\n", t2);
> +
> +     t1 = rdmsr(IA32_TSC_ADJUST);
> +     printf("Initial rdmsr IA32_TSC_ADJUST: %lld\n", t1);
> +     
> +     t5 = 100000000000ull;
> +     wrtsc(t5);
> +     t1 = rdmsr(IA32_TSC_ADJUST);
> +     printf("wrtsc %lld, rdmsr IA32_TSC_ADJUST: %lld\n", t5, t1);
> +
> +     wrmsr(IA32_TSC_ADJUST, t3);
> +     t2 = rdtsc();
> +     t1 = rdmsr(IA32_TSC_ADJUST);
> +     printf( "wrmsr IA32_TSC_ADJUST %lld, rdmsr IA32_TSC_ADJUST: %lld, 
> rdtsc: %lld\n", t3, t1, t2);
> +     
> +     t3 = 0xffff;
> +     t4 = rdtsc();
> +     wrmsr(IA32_TSC_ADJUST, t3);
> +     t2 = rdtsc();
> +     t1 = rdmsr(IA32_TSC_ADJUST);
> +     printf( "wrmsr IA32_TSC_ADJUST %lld, rdmsr IA32_TSC_ADJUST: %lld, 
> rdtsc: %lld\n", t3, t1, t2);
> +     lat = t2 - t4;
> +     printf("rdtsc/wrmsr/rdtsc latency %lld\n", lat);
> +     
> +     return 0;
> +}
> -- 
> 1.8.0.rc0
> 
> 
> 
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