From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43509) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WTEPd-00012Z-1G for qemu-devel@nongnu.org; Thu, 27 Mar 2014 13:48:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WTEPX-0004X7-0c for qemu-devel@nongnu.org; Thu, 27 Mar 2014 13:48:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:15779) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WTEPW-0004Wi-OL for qemu-devel@nongnu.org; Thu, 27 Mar 2014 13:48:14 -0400 Date: Thu, 27 Mar 2014 13:48:08 -0400 From: Luiz Capitulino Message-ID: <20140327134808.104dd50e@redhat.com> In-Reply-To: <20140319170353.4428b501@redhat.com> References: <20140319170353.4428b501@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 for-2.0] target-i386: x86_cpu_get_phys_page_debug(): support 1GB page translation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: peter.maydell@linaro.org Cc: jan.kiszka@siemens.com, pbonzini@redhat.com, qemu-devel , afaerber@suse.de On Wed, 19 Mar 2014 17:03:53 -0400 Luiz Capitulino wrote: > Linux guests, when using more than 4GB of RAM, may end up using 1GB pages > to store (kernel) data. When this happens, we're unable to debug a running > Linux kernel with GDB: > > (gdb) p node_data[0]->node_id > Cannot access memory at address 0xffff88013fffd3a0 > (gdb) > > GDB returns this error because x86_cpu_get_phys_page_debug() doesn't support > translating 1GB pages in IA-32e paging mode and returns an error to GDB. > > This commit adds support for 1GB page translation for IA32e paging. Peter, can you pick up this one please? > > Signed-off-by: Luiz capitulino > --- > > - I'm proposing this patch for 2.0 because GDB debugging of large Linux > guests is kind of broken > > - Changelog v2: > - Move PS bit handling to if (env->hflags & HF_LMA_MASK) block > - Update changelog > > target-i386/helper.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/target-i386/helper.c b/target-i386/helper.c > index 4f447b8..7cee501 100644 > --- a/target-i386/helper.c > +++ b/target-i386/helper.c > @@ -941,6 +941,14 @@ hwaddr x86_cpu_get_phys_page_debug(CPUState *cs, vaddr addr) > pdpe = ldq_phys(cs->as, pdpe_addr); > if (!(pdpe & PG_PRESENT_MASK)) > return -1; > + > + if (pdpe & PG_PSE_MASK) { > + page_size = 1024 * 1024 * 1024; > + pte = pdpe & ~( (page_size - 1) & ~0xfff); > + pte &= ~(PG_NX_MASK | PG_HI_USER_MASK); > + goto out; > + } > + > } else > #endif > { > @@ -993,6 +1001,7 @@ hwaddr x86_cpu_get_phys_page_debug(CPUState *cs, vaddr addr) > pte = pte & env->a20_mask; > } > > +out: > page_offset = (addr & TARGET_PAGE_MASK) & (page_size - 1); > paddr = (pte & TARGET_PAGE_MASK) + page_offset; > return paddr;