Re: [PATCH kvm-unit-tests] svm: Verify the effect of V_INTR_MASKING on INTR interrupts

[Paolo Bonzini <pbonzini@redhat.com>]

On 03/12/19 14:24, Cathy Avery wrote:
> The test confirms the influence of the V_INTR_MASKING bit
> on RFLAGS.IF. The expectation is while running a guest
> with V_INTR_MASKING cleared to zero:
> 
> - EFLAGS.IF controls both virtual and physical interrupts.
> 
> While running a guest with V_INTR_MASKING set to 1:
> 
> - The host EFLAGS.IF at the time of the VMRUN is saved and
>   controls physical interrupts while the guest is running.
> 
> - The guest value of EFLAGS.IF controls virtual interrupts only.
> 
> As discussed previously, this patch also modifies the vmrun
> loop ( test_run ) to allow running with HIF=0

Looks good, just a couple nits below.

> Signed-off-by: Cathy Avery <cavery@redhat.com>
> ---
>  x86/svm.c | 106 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 104 insertions(+), 2 deletions(-)
> 
> diff --git a/x86/svm.c b/x86/svm.c
> index 0360d8d..fb5796f 100644
> --- a/x86/svm.c
> +++ b/x86/svm.c
> @@ -44,6 +44,8 @@ u64 runs;
>  u8 *io_bitmap;
>  u8 io_bitmap_area[16384];
>  
> +u64 set_host_if = 1;

"u8 set_host_if;" here

> +
>  #define MSR_BITMAP_SIZE 8192
>  
>  u8 *msr_bitmap;
> @@ -266,21 +268,24 @@ static void test_run(struct test *test, struct vmcb *vmcb)


... "set_host_if = 1;" before invoking the ->prepare function...

>          tsc_start = rdtsc();
>          asm volatile (
>              "clgi \n\t"
> +            "cmp $0, set_host_if\n\t"

... and cmpb here.

> +            "jz 1f\n\t"
> +            "sti \n\t"
> +            "1: \n\t"
>              "vmload \n\t"
>              "mov regs+0x80, %%r15\n\t"  // rflags
>              "mov %%r15, 0x170(%0)\n\t"
>              "mov regs, %%r15\n\t"       // rax
>              "mov %%r15, 0x1f8(%0)\n\t"
>              LOAD_GPR_C
> -            "sti \n\t"		// only used if V_INTR_MASKING=1
>              "vmrun \n\t"
> -            "cli \n\t"
>              SAVE_GPR_C
>              "mov 0x170(%0), %%r15\n\t"  // rflags
>              "mov %%r15, regs+0x80\n\t"
>              "mov 0x1f8(%0), %%r15\n\t"  // rax
>              "mov %%r15, regs\n\t"
>              "vmsave \n\t"
> +            "cli \n\t"
>              "stgi"
>              : : "a"(vmcb_phys)
>              : "rbx", "rcx", "rdx", "rsi",
> @@ -307,6 +312,7 @@ static bool default_supported(void)
>  static void default_prepare(struct test *test)
>  {
>      vmcb_ident(test->vmcb);
> +    cli();

I think this is not needed, perhaps it's a relic of rebasing your
previous patch?

Thanks,

Paolo

>  }
>  
>  static bool default_finished(struct test *test)
> @@ -1386,6 +1392,99 @@ static bool pending_event_check(struct test *test)
>      return get_test_stage(test) == 2;
>  }
>  
> +static void pending_event_prepare_vmask(struct test *test)
> +{
> +    default_prepare(test);
> +
> +    pending_event_ipi_fired = false;
> +
> +    set_host_if = 0;
> +
> +    handle_irq(0xf1, pending_event_ipi_isr);
> +
> +    apic_icr_write(APIC_DEST_SELF | APIC_DEST_PHYSICAL |
> +              APIC_DM_FIXED | 0xf1, 0);
> +
> +    set_test_stage(test, 0);
> +}
> +
> +static void pending_event_test_vmask(struct test *test)
> +{
> +    if (pending_event_ipi_fired == true) {
> +        set_test_stage(test, -1);
> +        report("Interrupt preceeded guest", false);
> +        vmmcall();
> +    }
> +
> +    irq_enable();
> +    asm volatile ("nop");
> +    irq_disable();
> +
> +    if (pending_event_ipi_fired != true) {
> +        set_test_stage(test, -1);
> +        report("Interrupt not triggered by guest", false);
> +    }
> +
> +    vmmcall();
> +
> +    irq_enable();
> +    asm volatile ("nop");
> +    irq_disable();
> +}
> +
> +static bool pending_event_finished_vmask(struct test *test)
> +{
> +    if ( test->vmcb->control.exit_code != SVM_EXIT_VMMCALL) {
> +        report("VM_EXIT return to host is not EXIT_VMMCALL exit reason 0x%x", false,
> +                test->vmcb->control.exit_code);
> +        return true;
> +    }
> +
> +    switch (get_test_stage(test)) {
> +    case 0:
> +        test->vmcb->save.rip += 3;
> +
> +        pending_event_ipi_fired = false;
> +
> +        test->vmcb->control.int_ctl |= V_INTR_MASKING_MASK;
> +
> +        apic_icr_write(APIC_DEST_SELF | APIC_DEST_PHYSICAL |
> +              APIC_DM_FIXED | 0xf1, 0);
> +
> +        break;
> +
> +    case 1:
> +        if (pending_event_ipi_fired == true) {
> +            report("Interrupt triggered by guest", false);
> +            return true;
> +        }
> +
> +        irq_enable();
> +        asm volatile ("nop");
> +        irq_disable();
> +
> +        if (pending_event_ipi_fired != true) {
> +            report("Interrupt not triggered by host", false);
> +            return true;
> +        }
> +
> +        break;
> +
> +    default:
> +        return true;
> +    }
> +
> +    inc_test_stage(test);
> +
> +    return get_test_stage(test) == 2;
> +}
> +
> +static bool pending_event_check_vmask(struct test *test)
> +{
> +    set_host_if = 1;
> +    return get_test_stage(test) == 2;
> +}
> +
>  static struct test tests[] = {
>      { "null", default_supported, default_prepare, null_test,
>        default_finished, null_check },
> @@ -1438,6 +1537,9 @@ static struct test tests[] = {
>        lat_svm_insn_finished, lat_svm_insn_check },
>      { "pending_event", default_supported, pending_event_prepare,
>        pending_event_test, pending_event_finished, pending_event_check },
> +    { "pending_event_vmask", default_supported, pending_event_prepare_vmask,
> +      pending_event_test_vmask, pending_event_finished_vmask,
> +      pending_event_check_vmask },
>  };
>  
>  int main(int ac, char **av)
>