Re: [Qemu-arm] [PATCH v16 10/10] target-arm: kvm64: handle SIGBUS signal from kernel or KVM

[Peter Maydell]

On Mon, 13 May 2019 at 13:46, Dongjiu Geng <address@hidden> wrote:
>
> Add SIGBUS signal handler. In this handler, it checks the SIGBUS type,
> translates the host VA delivered by host to guest PA, then fill this PA
> to guest APEI GHES memory, then notify guest according to the SIGBUS type.
>
> If guest accesses the poisoned memory, it generates Synchronous External
> Abort(SEA). Then host kernel gets an APEI notification and call 
> memory_failure()
> to unmapped the affected page for the guest's stage 2, finally return
> to guest.
>
> Guest continues to access PG_hwpoison page, it will trap to KVM as stage2 
> fault,
> then a SIGBUS_MCEERR_AR synchronous signal is delivered to Qemu, Qemu record 
> this
> error address into guest APEI GHES memory and notify guest using
> Synchronous-External-Abort(SEA).
>
> Suggested-by: James Morse <address@hidden>
> Signed-off-by: Dongjiu Geng <address@hidden>


> +void kvm_arch_on_sigbus_vcpu(CPUState *c, int code, void *addr)
> +{
> +    ARMCPU *cpu = ARM_CPU(c);
> +    CPUARMState *env = &cpu->env;
> +    ram_addr_t ram_addr;
> +    hwaddr paddr;
> +
> +    assert(code == BUS_MCEERR_AR || code == BUS_MCEERR_AO);
> +
> +    if (addr) {
> +        ram_addr = qemu_ram_addr_from_host(addr);
> +        if (ram_addr != RAM_ADDR_INVALID &&
> +            kvm_physical_memory_addr_from_host(c->kvm_state, addr, &paddr)) {
> +            kvm_hwpoison_page_add(ram_addr);
> +            /* Asynchronous signal will be masked by main thread, so
> +             * only handle synchronous signal.
> +             */
> +            if (code == BUS_MCEERR_AR) {
> +                kvm_cpu_synchronize_state(c);
> +                if (GHES_CPER_FAIL != 
> ghes_record_errors(ACPI_HEST_NOTIFY_SEA, paddr)) {
> +                    kvm_inject_arm_sea(c);
> +                } else {
> +                    fprintf(stderr, "failed to record the error\n");
> +                }
> +            }
> +            return;
> +        }
> +        fprintf(stderr, "Hardware memory error for memory used by "
> +                "QEMU itself instead of guest system!\n");
> +    }
> +
> +    if (code == BUS_MCEERR_AR) {
> +        fprintf(stderr, "Hardware memory error!\n");
> +        exit(1);
> +    }
> +}

This code appears to still be unconditionally trying to
notify the guest of the error via the ACPI tables without
checking whether those ACPI tables even exist. I told you
about this in a previous round of review :-(

thanks
-- PMM