From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1gDWHp-0005g9-Fo for mharc-grub-devel@gnu.org; Fri, 19 Oct 2018 11:02:01 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36812) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gDWHj-0005cY-1v for grub-devel@gnu.org; Fri, 19 Oct 2018 11:02:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gDWHf-0001j6-3Q for grub-devel@gnu.org; Fri, 19 Oct 2018 11:01:55 -0400 Received: from mx2.suse.de ([195.135.220.15]:58924 helo=mx1.suse.de) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gDWHe-0001ez-PP for grub-devel@gnu.org; Fri, 19 Oct 2018 11:01:51 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 6DF1EAF99; Fri, 19 Oct 2018 15:01:48 +0000 (UTC) Subject: Re: [Xen-devel] [PATCH v2 10/18] xen: setup hypercall page for PVH To: Daniel Kiper Cc: hans@knorrie.org, grub-devel@gnu.org, phcoder@gmail.com, xen-devel@lists.xen.org References: <20181009110317.6022-1-jgross@suse.com> <20181009110317.6022-11-jgross@suse.com> <20181019123014.GG4422@olila.i.net-space.pl> From: Juergen Gross Openpgp: preference=signencrypt Autocrypt: addr=jgross@suse.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181019123014.GG4422@olila.i.net-space.pl> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x (no timestamps) [generic] X-Received-From: 195.135.220.15 X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Oct 2018 15:02:00 -0000 On 19/10/2018 14:30, Daniel Kiper wrote: > On Tue, Oct 09, 2018 at 01:03:09PM +0200, Juergen Gross wrote: >> Add the needed code to setup the hypercall page for calling into the >> Xen hypervisor. >> >> Signed-off-by: Juergen Gross >> --- >> grub-core/kern/i386/xen/pvh.c | 70 +++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 70 insertions(+) >> >> diff --git a/grub-core/kern/i386/xen/pvh.c b/grub-core/kern/i386/xen/pvh.c >> index 182ef95f9..c1b1cf8db 100644 >> --- a/grub-core/kern/i386/xen/pvh.c >> +++ b/grub-core/kern/i386/xen/pvh.c >> @@ -20,14 +20,84 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> >> grub_uint64_t grub_rsdp_addr; >> >> +static struct { char _entry[32]; } hypercall_page[128] >> + __attribute__ ((aligned (GRUB_XEN_PAGE_SIZE))); >> + >> +static grub_uint32_t xen_cpuid_base; >> + >> +static void >> +grub_xen_early_halt (void) >> +{ >> + asm volatile ("hlt"); >> +} >> + >> +static void >> +grub_xen_cpuid_base (void) >> +{ >> + grub_uint32_t base, eax, signature[3]; >> + >> + for (base = 0x40000000; base < 0x40010000; base += 0x100) >> + { >> + grub_cpuid (base, eax, signature[0], signature[1], signature[2]); >> + if (!grub_memcmp ("XenVMMXenVMM", signature, 12) && (eax - base) >= 2) >> + { >> + xen_cpuid_base = base; >> + return; >> + } >> + } >> + >> + grub_xen_early_halt (); >> +} >> + >> +static void >> +grub_xen_setup_hypercall_page (void) >> +{ >> + grub_uint32_t msr, pfn, eax, ebx, ecx, edx; >> + >> + grub_cpuid (xen_cpuid_base + 2, eax, ebx, ecx, edx); >> + msr = ebx; >> + pfn = (grub_uint32_t) (&hypercall_page[0]); >> + >> + asm volatile ("wrmsr" : : "c" (msr), "a" (pfn), "d" (0) : "memory"); >> +} >> + >> +int >> +grub_xen_hypercall (grub_uint32_t callno, grub_uint32_t a0, >> + grub_uint32_t a1, grub_uint32_t a2, >> + grub_uint32_t a3, grub_uint32_t a4, >> + grub_uint32_t a5 __attribute__ ((unused))) >> +{ >> + register unsigned long __res asm("eax"); >> + register unsigned long __arg0 asm("ebx") = __arg0; >> + register unsigned long __arg1 asm("ecx") = __arg1; >> + register unsigned long __arg2 asm("edx") = __arg2; >> + register unsigned long __arg3 asm("esi") = __arg3; >> + register unsigned long __arg4 asm("edi") = __arg4; > > Why do we need this play with registers. Does not asm below > work with "a", "b", ... like above? Probably, yes. This was inspired by Linux 32-bit version. I can use the mini-os variant which combines Andrew's suggestion and yours. Juergen