[{"id":3683614,"web_url":"http://patchwork.ozlabs.org/comment/3683614/","msgid":"","list_archive_url":null,"date":"2026-04-28T17:49:21","subject":"Re: [PATCH 4/6] target/i386/mshv: hv_vp_register_page setup for the\n vcpu","submitter":{"id":91318,"url":"http://patchwork.ozlabs.org/api/people/91318/","name":"Mohamed Mediouni","email":"mohamed@unpredictable.fr"},"content":"> On 28. Apr 2026, at 15:50, Doru Blânzeanu wrote:\n> \n> When the vcpu is created, call mmap to configure access to the register page.\n> \n> Update CPUArchState to store a pointer to the mmapped hv_vp_register_page.\n> \n> Signed-off-by: Doru Blânzeanu \n> ---\n> target/i386/cpu.h | 3 +++\n> target/i386/mshv/mshv-cpu.c | 18 ++++++++++++++++++\n> 2 files changed, 21 insertions(+)\n> \n> diff --git a/target/i386/cpu.h b/target/i386/cpu.h\n> index 0b539155c4..0108e2157b 100644\n> --- a/target/i386/cpu.h\n> +++ b/target/i386/cpu.h\n> @@ -2016,6 +2016,9 @@ typedef struct CPUArchState {\n> uint64_t msr_bndcfgs;\n> uint64_t efer;\n> \n> + /* Shared register page */\n> + struct hv_vp_register_page *regs_page;\n> +\n> /* Beginning of state preserved by INIT (dummy marker). */\n> struct {} start_init_save;\n> \n> diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c\n> index 9defd05db6..42b6fb1912 100644\n> --- a/target/i386/mshv/mshv-cpu.c\n> +++ b/target/i386/mshv/mshv-cpu.c\n> @@ -1595,6 +1595,19 @@ void mshv_arch_init_vcpu(CPUState *cpu)\n> + sizeof(hv_input_get_vp_registers)\n>> HV_HYP_PAGE_SIZE));\n> \n> +\n> + /* mmap the registers page */\n> + void *rp = mmap(NULL, page, PROT_READ | PROT_WRITE,\n> + MAP_SHARED, mshv_vcpufd(cpu),\n> + MSHV_VP_MMAP_OFFSET_REGISTERS * page);\n> + if (rp == MAP_FAILED) {\n> + warn_report(\"register page mmap failed, falling back to hypercalls: %s\",\n> + strerror(errno));\nHi,\n\nI think it’s better to make this fatal tbh, the perf hit is just way\ntoo big imo.\n\nOtherwise,\n\nReviewed-by: Mohamed Mediouni \n\n> + env->regs_page = NULL;\n> + } else {\n> + env->regs_page = (struct hv_vp_register_page *) rp;\n> + }\n> +\n> state->hvcall_args.base = mem;\n> state->hvcall_args.input_page = mem;\n> state->hvcall_args.output_page = (uint8_t *)mem + page;\n> @@ -1608,6 +1621,11 @@ void mshv_arch_destroy_vcpu(CPUState *cpu)\n> CPUX86State *env = &x86_cpu->env;\n> AccelCPUState *state = cpu->accel;\n> \n> + /* Unmap the register page */\n> + if (env->regs_page) {\n> + munmap(env->regs_page, HV_HYP_PAGE_SIZE);\n> + env->regs_page = NULL;\n> + }\n> g_free(state->hvcall_args.base);\n> state->hvcall_args = (MshvHvCallArgs){0};\n> g_clear_pointer(&env->emu_mmio_buf, g_free);\n> -- \n> 2.53.0\n> \n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=unpredictable.fr header.i=@unpredictable.fr\n header.a=rsa-sha256 header.s=sig1 header.b=H8vofbnv;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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