On Tue, Oct 6, 2020 at 2:26 PM Oliver Upton <oupton@xxxxxxxxxx> wrote:
>
> If a guest blocks interrupts for the entirety of running in root mode
> (RFLAGS.IF=0), a pending interrupt corresponding to the posted-interrupt
> vector set in the VMCS should result in an interrupt posting to the vIRR
> at VM-entry. However, on KVM this is not the case. The pending interrupt
> is not recognized as the posted-interrupt vector and instead results in
> an external interrupt VM-exit.
>
> Add a regression test to exercise this issue.
>
> Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
> ---
> lib/x86/asm/bitops.h | 8 +++++
> x86/vmx_tests.c | 76 ++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 84 insertions(+)
>
> diff --git a/lib/x86/asm/bitops.h b/lib/x86/asm/bitops.h
> index 13a25ec9853d..ce5743538f65 100644
> --- a/lib/x86/asm/bitops.h
> +++ b/lib/x86/asm/bitops.h
> @@ -13,4 +13,12 @@
>
> #define HAVE_BUILTIN_FLS 1
>
> +static inline void test_and_set_bit(long nr, unsigned long *addr)
> +{
> + asm volatile("lock; bts %1, %0"
> + : "+m" (*addr)
> + : "Ir" (nr)
> + : "memory");
> +}
> +
> #endif
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index d2084ae9e8ce..9ba9a5d452a2 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -10430,6 +10430,81 @@ static void atomic_switch_overflow_msrs_test(void)
> test_skip("Test is only supported on KVM");
> }
>
> +#define PI_VECTOR 0xe0
> +#define PI_TEST_VECTOR 0x21
> +
> +static void enable_posted_interrupts(void)
> +{
> + void *pi_desc = alloc_page();
> +
> + vmcs_set_bits(PIN_CONTROLS, PIN_POST_INTR);
> + vmcs_set_bits(EXI_CONTROLS, EXI_INTA);
> + vmcs_write(PINV, PI_VECTOR);
> + vmcs_write(POSTED_INTR_DESC_ADDR, (u64)pi_desc);
> +}
> +
> +static unsigned long *get_pi_desc(void)
> +{
> + return (unsigned long *)vmcs_read(POSTED_INTR_DESC_ADDR);
> +}
> +
> +static void post_interrupt(u8 vector, u32 dest)
> +{
> + unsigned long *pi_desc = get_pi_desc();
> +
> + test_and_set_bit(vector, pi_desc);
> + test_and_set_bit(256, pi_desc);
> + apic_icr_write(PI_VECTOR, dest);
> +}
> +
> +static struct vmx_posted_interrupt_test_args {
> + bool isr_fired;
> +} vmx_posted_interrupt_test_args;
> +
> +static void vmx_posted_interrupt_test_isr(isr_regs_t *regs)
> +{
> + volatile struct vmx_posted_interrupt_test_args *args
> + = &vmx_posted_interrupt_test_args;
> +
> + args->isr_fired = true;
> + eoi();
> +}
> +
> +static void vmx_posted_interrupt_test_guest(void)
> +{
> + handle_irq(PI_TEST_VECTOR, vmx_posted_interrupt_test_isr);
> + irq_enable();
> + vmcall();
> + asm volatile("nop");
> + vmcall();
> +}
> +
> +static void vmx_posted_interrupt_test(void)
> +{
> + volatile struct vmx_posted_interrupt_test_args *args
> + = &vmx_posted_interrupt_test_args;
> +
> + if (!cpu_has_apicv()) {
> + report_skip(__func__);
> + return;
> + }
> +
> + enable_vid();
> + enable_posted_interrupts();
> + test_set_guest(vmx_posted_interrupt_test_guest);
> +
> + enter_guest();
> + skip_exit_vmcall();
> +
> + irq_disable();
> + post_interrupt(PI_TEST_VECTOR, apic_id());
> + enter_guest();
> +
> + skip_exit_vmcall();
> + TEST_ASSERT(args->isr_fired);
> + enter_guest();
> +}
> +
> #define TEST(name) { #name, .v2 = name }
>
> /* name/init/guest_main/exit_handler/syscall_handler/guest_regs */
> @@ -10533,5 +10608,6 @@ struct vmx_test vmx_tests[] = {
> TEST(rdtsc_vmexit_diff_test),
> TEST(vmx_mtf_test),
> TEST(vmx_mtf_pdpte_test),
> + TEST(vmx_posted_interrupt_test),
> { NULL, NULL, NULL, NULL, NULL, {0} },
> };
> --
> 2.28.0.806.g8561365e88-goog
>
Ping.
