Re: [PATCH] i386: hvf: Reset IRQ inhibition after moving RIP

[Cameron Esfahani]

Reviewed-by: Cameron Esfahani <address@hidden>

LGTM.

Cameron Esfahani
address@hidden

"There are times in the life of a nation when the only place a decent man can 
find himself is in prison."



> On Mar 28, 2020, at 10:44 AM, Roman Bolshakov <address@hidden> wrote:
> 
> The sequence of instructions exposes an issue:
>  sti
>  hlt
> 
> Interrupts cannot be delivered to hvf after hlt instruction cpu because
> HF_INHIBIT_IRQ_MASK is set just before hlt is handled and never reset
> after moving instruction pointer beyond hlt.
> 
> So, after hvf_vcpu_exec() returns, CPU thread gets locked up forever in
> qemu_wait_io_event() (cpu_thread_is_idle() evaluates inhibition
> flag and considers the CPU idle if the flag is set).
> 
> Cc: Cameron Esfahani <address@hidden>
> Signed-off-by: Roman Bolshakov <address@hidden>
> ---
> target/i386/hvf/vmx.h | 3 +++
> 1 file changed, 3 insertions(+)
> 
> diff --git a/target/i386/hvf/vmx.h b/target/i386/hvf/vmx.h
> index 03d2c79b9c..ce2a1532d5 100644
> --- a/target/i386/hvf/vmx.h
> +++ b/target/i386/hvf/vmx.h
> @@ -167,6 +167,8 @@ static inline void macvm_set_cr4(hv_vcpuid_t vcpu, 
> uint64_t cr4)
> 
> static inline void macvm_set_rip(CPUState *cpu, uint64_t rip)
> {
> +    X86CPU *x86_cpu = X86_CPU(cpu);
> +    CPUX86State *env = &x86_cpu->env;
>     uint64_t val;
> 
>     /* BUG, should take considering overlap.. */
> @@ -176,6 +178,7 @@ static inline void macvm_set_rip(CPUState *cpu, uint64_t 
> rip)
>    val = rvmcs(cpu->hvf_fd, VMCS_GUEST_INTERRUPTIBILITY);
>    if (val & (VMCS_INTERRUPTIBILITY_STI_BLOCKING |
>                VMCS_INTERRUPTIBILITY_MOVSS_BLOCKING)) {
> +        env->hflags &= ~HF_INHIBIT_IRQ_MASK;
>         wvmcs(cpu->hvf_fd, VMCS_GUEST_INTERRUPTIBILITY,
>                val & ~(VMCS_INTERRUPTIBILITY_STI_BLOCKING |
>                VMCS_INTERRUPTIBILITY_MOVSS_BLOCKING));
> -- 
> 2.24.1
> 
>