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Re: [PATCH] i386: hvf: Reset IRQ inhibition after moving RIP
From: |
Paolo Bonzini |
Subject: |
Re: [PATCH] i386: hvf: Reset IRQ inhibition after moving RIP |
Date: |
Mon, 30 Mar 2020 14:43:03 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 |
On 28/03/20 18:44, Roman Bolshakov 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));
>
Queued, thanks!
Paolo