From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: Re: [PATCH v2] minios: don't rely on specific page table allocation scheme Date: Fri, 20 Nov 2015 14:09:02 +0000 Message-ID: <20151120140902.GZ1495@citrix.com> References: <1448027577-23963-1-git-send-email-jgross@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1448027577-23963-1-git-send-email-jgross@suse.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Juergen Gross Cc: wei.liu2@citrix.com, Ian.Campbell@citrix.com, stefano.stabellini@eu.citrix.com, ian.jackson@eu.citrix.com, xen-devel@lists.xen.org, samuel.thibault@ens-lyon.org List-Id: xen-devel@lists.xenproject.org On Fri, Nov 20, 2015 at 02:52:57PM +0100, Juergen Gross wrote: > Today mini-os is making assumptions how the page tables it is started > with are being allocated. Especially it is using the number of page > table frames to calculate which is the first unmapped pfn. > > Instead of relying on page table number assumptions just look into the > page tables to find the first pfn not already mapped. > > Signed-off-by: Juergen Gross > --- > Changes in V2: > - remove need_pt_frame() as it simplifies code (suggested by Wei Liu) > > --- > arch/x86/mm.c | 81 ++++++++++----------------------------------------- > include/x86/arch_mm.h | 7 ----- > 2 files changed, 15 insertions(+), 73 deletions(-) > > diff --git a/arch/x86/mm.c b/arch/x86/mm.c > index 9c6d1b8..b828efc 100644 > --- a/arch/x86/mm.c > +++ b/arch/x86/mm.c > @@ -132,61 +132,6 @@ static void new_pt_frame(unsigned long *pt_pfn, unsigned long prev_l_mfn, > } > > /* > - * Checks if a pagetable frame is needed at 'level' to map a given > - * address. Note, this function is specific to the initial page table > - * building. > - */ > -static int need_pt_frame(unsigned long va, int level) > -{ > - unsigned long hyp_virt_start = HYPERVISOR_VIRT_START; > -#if defined(__x86_64__) > - unsigned long hyp_virt_end = HYPERVISOR_VIRT_END; > -#else > - unsigned long hyp_virt_end = 0xffffffff; > -#endif > - > - /* In general frames will _not_ be needed if they were already > - allocated to map the hypervisor into our VA space */ > -#if defined(__x86_64__) > - if ( level == L3_FRAME ) > - { > - if ( l4_table_offset(va) >= > - l4_table_offset(hyp_virt_start) && > - l4_table_offset(va) <= > - l4_table_offset(hyp_virt_end)) > - return 0; > - return 1; > - } > - else > -#endif > - > - if ( level == L2_FRAME ) > - { > -#if defined(__x86_64__) > - if ( l4_table_offset(va) >= > - l4_table_offset(hyp_virt_start) && > - l4_table_offset(va) <= > - l4_table_offset(hyp_virt_end)) > -#endif > - if ( l3_table_offset(va) >= > - l3_table_offset(hyp_virt_start) && > - l3_table_offset(va) <= > - l3_table_offset(hyp_virt_end)) > - return 0; > - > - return 1; > - } > - else > - /* Always need l1 frames */ > - if ( level == L1_FRAME ) > - return 1; > - > - printk("ERROR: Unknown frame level %d, hypervisor %llx,%llx\n", > - level, hyp_virt_start, hyp_virt_end); > - return -1; > -} > - > -/* Strangely git am rejects the above hunk. I manually fix that up in my tree and test again. All my tests in previous email passed. Reviewed-by: Wei Liu Tested-by: Wei Liu