On Tue, May 05, 2026 at 09:50:25PM +0300, Doru Blânzeanu wrote:
> When the vcpu is created, call mmap to configure access to the register page.
> In case the call to mmap fails, we log an error and continue with the
> previous logic (using hypercalls).
>
> Update CPUArchState to store a pointer to the mmapped hv_vp_register_page.
>
> Signed-off-by: Doru Blânzeanu <[email protected]>
> ---
> target/i386/cpu.h | 5 +++++
> target/i386/mshv/mshv-cpu.c | 22 ++++++++++++++++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 16de67e546..fd4c3712b1 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -2019,6 +2019,11 @@ typedef struct CPUArchState {
> uint64_t msr_bndcfgs;
> uint64_t efer;
>
> +#ifdef CONFIG_MSHV
> + /* Shared register page */
> + struct hv_vp_register_page *regs_page;
> +#endif
since this is declared before this marker
/* Fields up to this point are cleared by a CPU reset */
struct {} end_reset_fields;
the pointer will be zeroed out on init, best move it after the
emu_mmio_buf field.
> +
> /* Beginning of state preserved by INIT (dummy marker). */
> struct {} start_init_save;
>
> diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c
> index 9defd05db6..3a3c269c33 100644
> --- a/target/i386/mshv/mshv-cpu.c
> +++ b/target/i386/mshv/mshv-cpu.c
> @@ -1587,6 +1587,7 @@ void mshv_arch_init_vcpu(CPUState *cpu)
> CPUX86State *env = &x86_cpu->env;
> AccelCPUState *state = cpu->accel;
> size_t page = HV_HYP_PAGE_SIZE;
> + void *regs_page;
> void *mem = qemu_memalign(page, 2 * page);
>
> /* sanity check, to make sure we don't overflow the page */
> @@ -1595,6 +1596,22 @@ void mshv_arch_init_vcpu(CPUState *cpu)
> + sizeof(hv_input_get_vp_registers)
> > HV_HYP_PAGE_SIZE));
>
> +
> + /* mmap the registers page */
> + regs_page = mmap(NULL, page, PROT_READ | PROT_WRITE,
> + MAP_SHARED, mshv_vcpufd(cpu),
> + MSHV_VP_MMAP_OFFSET_REGISTERS * page);
> + if (regs_page == MAP_FAILED) {
> + /*
> + * Error is not fatal, but we won't be able to use the
> + * fast path for register access
> + */
> + error_report("register page mmap failed: %s", strerror(errno));
> + env->regs_page = NULL;
> + } else {
> + env->regs_page = (struct hv_vp_register_page *) regs_page;
> + }
> +
> state->hvcall_args.base = mem;
> state->hvcall_args.input_page = mem;
> state->hvcall_args.output_page = (uint8_t *)mem + page;
> @@ -1608,6 +1625,11 @@ void mshv_arch_destroy_vcpu(CPUState *cpu)
> CPUX86State *env = &x86_cpu->env;
> AccelCPUState *state = cpu->accel;
>
> + /* Unmap the register page */
> + if (env->regs_page) {
> + munmap(env->regs_page, HV_HYP_PAGE_SIZE);
> + env->regs_page = NULL;
> + }
> g_free(state->hvcall_args.base);
> state->hvcall_args = (MshvHvCallArgs){0};
> g_clear_pointer(&env->emu_mmio_buf, g_free);
> --
> 2.53.0
