[{"id":3687127,"web_url":"http://patchwork.ozlabs.org/comment/3687127/","msgid":"","list_archive_url":null,"date":"2026-05-06T14:36:13","subject":"Re: [PATCH v2 4/7] target/i386/mshv: hv_vp_register_page setup for\n the vcpu","submitter":{"id":90753,"url":"http://patchwork.ozlabs.org/api/people/90753/","name":"Magnus Kulke","email":"magnuskulke@linux.microsoft.com"},"content":"On Tue, May 05, 2026 at 09:50:25PM +0300, Doru Blânzeanu wrote:\n> When the vcpu is created, call mmap to configure access to the register page.\n> In case the call to mmap fails, we log an error and continue with the\n> previous logic (using hypercalls).\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 | 5 +++++\n> target/i386/mshv/mshv-cpu.c | 22 ++++++++++++++++++++++\n> 2 files changed, 27 insertions(+)\n> \n> diff --git a/target/i386/cpu.h b/target/i386/cpu.h\n> index 16de67e546..fd4c3712b1 100644\n> --- a/target/i386/cpu.h\n> +++ b/target/i386/cpu.h\n> @@ -2019,6 +2019,11 @@ typedef struct CPUArchState {\n> uint64_t msr_bndcfgs;\n> uint64_t efer;\n> \n> +#ifdef CONFIG_MSHV\n> + /* Shared register page */\n> + struct hv_vp_register_page *regs_page;\n> +#endif\n\nsince this is declared before this marker\n\n /* Fields up to this point are cleared by a CPU reset */\n struct {} end_reset_fields;\n\nthe pointer will be zeroed out on init, best move it after the\nemu_mmio_buf field.\n\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..3a3c269c33 100644\n> --- a/target/i386/mshv/mshv-cpu.c\n> +++ b/target/i386/mshv/mshv-cpu.c\n> @@ -1587,6 +1587,7 @@ void mshv_arch_init_vcpu(CPUState *cpu)\n> CPUX86State *env = &x86_cpu->env;\n> AccelCPUState *state = cpu->accel;\n> size_t page = HV_HYP_PAGE_SIZE;\n> + void *regs_page;\n> void *mem = qemu_memalign(page, 2 * page);\n> \n> /* sanity check, to make sure we don't overflow the page */\n> @@ -1595,6 +1596,22 @@ 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> + regs_page = mmap(NULL, page, PROT_READ | PROT_WRITE,\n> + MAP_SHARED, mshv_vcpufd(cpu),\n> + MSHV_VP_MMAP_OFFSET_REGISTERS * page);\n> + if (regs_page == MAP_FAILED) {\n> + /*\n> + * Error is not fatal, but we won't be able to use the\n> + * fast path for register access\n> + */\n> + error_report(\"register page mmap failed: %s\", strerror(errno));\n> + env->regs_page = NULL;\n> + } else {\n> + env->regs_page = (struct hv_vp_register_page *) regs_page;\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 +1625,11 @@ 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","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 (1024-bit key;\n unprotected) header.d=linux.microsoft.com header.i=@linux.microsoft.com\n header.a=rsa-sha256 header.s=default header.b=M7SI55G/;\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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a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com;\n s=default; t=1778078175;\n bh=FKUfSDsIXOoZFWgGKOL6KFKf7v4gDq85YHXef0xMwsw=;\n h=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n b=M7SI55G/WcRHfMYvgmBXam9yrGusXPCojVPY6LZwGshuEmLlhfJo5V8HOqpRA0GcU\n 3c2AQnyAkQ71cjDwVlk9EAG/OU0qMFew5Htvc8TkoeRjRENMGmz7KzFaJknsN+npS9\n SlOACibC0/dffJNGsFSVkp+2nme8jCTfAKUjx1p0=","Date":"Wed, 6 May 2026 16:36:13 +0200","From":"Magnus Kulke ","To":"Doru =?iso-8859-1?q?Bl=E2nzeanu?= ","Cc":"qemu-devel@nongnu.org, Zhao Liu ,\n Wei Liu , Paolo Bonzini ","Subject":"Re: [PATCH v2 4/7] target/i386/mshv: hv_vp_register_page setup for\n the vcpu","Message-ID":"","References":"<20260505185028.237207-1-dblanzeanu@linux.microsoft.com>\n <20260505185028.237207-5-dblanzeanu@linux.microsoft.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=iso-8859-1","Content-Disposition":"inline","Content-Transfer-Encoding":"8bit","In-Reply-To":"<20260505185028.237207-5-dblanzeanu@linux.microsoft.com>","Received-SPF":"pass client-ip=13.77.154.182;\n envelope-from=magnuskulke@linux.microsoft.com; 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