Re: [PATCH 2/5] target/i386/mshv: abort when hv_vp_register_page setup fails

[Magnus Kulke <magnuskulke@linux.microsoft.com>]

On Wed, Jul 08, 2026 at 01:16:42AM +0300, Doru Blânzeanu wrote:
> In case the call to mmap fails, we log an error and abort to signal
> there is something wrong with the system.
> Check the register page version and compare with the expected version and
> abort in case of a mismatch.
> 
> Fixes: a173f8f170
> Signed-off-by: Doru Blânzeanu <dblanzeanu@linux.microsoft.com>
> ---
>  target/i386/mshv/mshv-cpu.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c
> index 1c433c408c..c782715497 100644
> --- a/target/i386/mshv/mshv-cpu.c
> +++ b/target/i386/mshv/mshv-cpu.c
> @@ -2049,6 +2049,7 @@ void mshv_arch_init_vcpu(CPUState *cpu)
>      CPUX86State *env = &x86_cpu->env;
>      AccelCPUState *state = cpu->accel;
>      size_t page = HV_HYP_PAGE_SIZE, xsave_len;
> +    void *regs_page;
>      void *mem = qemu_memalign(page, 2 * page);
>      int ret;
>      X86XSaveHeader *header;
> @@ -2060,15 +2061,20 @@ void mshv_arch_init_vcpu(CPUState *cpu)
>                        > HV_HYP_PAGE_SIZE));
>  
>      /* mmap the registers page */
> -    void *rp = mmap(NULL, page, PROT_READ | PROT_WRITE,
> +    regs_page = mmap(NULL, page, PROT_READ | PROT_WRITE,
>                      MAP_SHARED, mshv_vcpufd(cpu),
>                      MSHV_VP_MMAP_OFFSET_REGISTERS * page);
> -    if (rp == MAP_FAILED) {
> -        warn_report("register page mmap failed, falling back to hypercalls: %s",
> -                    strerror(errno));
> -        env->regs_page = NULL;
> -    } else {
> -        env->regs_page = (struct hv_vp_register_page *) rp;
> +    if (regs_page == MAP_FAILED) {
> +        /* This shouldn't fail, so we treat it as a fatal error */
> +        error_report("register page mmap failed: %s", strerror(errno));
> +        abort();
> +    }
> +    env->regs_page = (struct hv_vp_register_page *) regs_page;
> +
> +    if (env->regs_page->version != HV_VP_REGISTER_PAGE_VERSION_1) {
> +        error_report("register page version mismatch: got %u, expected %u",
> +                     env->regs_page->version, HV_VP_REGISTER_PAGE_VERSION_1);
> +        abort();
>      }
>  
>      state->hvcall_args.base = mem;
> -- 
> 2.53.0

Reviewed-by: Magnus Kulke <magnuskulke@linux.microsoft.com>