From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57237) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1al4hO-0003XQ-GX for qemu-devel@nongnu.org; Tue, 29 Mar 2016 21:13:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1al4hN-0006gm-GG for qemu-devel@nongnu.org; Tue, 29 Mar 2016 21:13:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41208) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1al4hN-0006ge-Ad for qemu-devel@nongnu.org; Tue, 29 Mar 2016 21:13:29 -0400 References: <1458872009-13342-1-git-send-email-jasowang@redhat.com> <1458872009-13342-5-git-send-email-jasowang@redhat.com> <20160328021800.GJ28183@pxdev.xzpeter.org> From: Jason Wang Message-ID: <56FB2834.2070904@redhat.com> Date: Wed, 30 Mar 2016 09:13:24 +0800 MIME-Version: 1.0 In-Reply-To: <20160328021800.GJ28183@pxdev.xzpeter.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH 4/8] exec: introduce address_space_get_iotlb_entry() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: mst@redhat.com, Peter Crosthwaite , qemu-devel@nongnu.org, cornelia.huck@de.ibm.com, pbonzini@redhat.com, Richard Henderson On 03/28/2016 10:18 AM, Peter Xu wrote: > On Fri, Mar 25, 2016 at 10:13:25AM +0800, Jason Wang wrote: >> This patch introduces a helper to query the iotlb entry for a >> possible iova. This will be used by later device IOTLB API to enable >> the capability for a dataplane (e.g vhost) to query the IOTLB. >> >> Cc: Paolo Bonzini >> Cc: Peter Crosthwaite >> Cc: Richard Henderson >> Signed-off-by: Jason Wang >> --- >> exec.c | 30 ++++++++++++++++++++++++++++++ >> include/exec/memory.h | 7 +++++++ >> 2 files changed, 37 insertions(+) >> >> diff --git a/exec.c b/exec.c >> index f398d21..31fac9f 100644 >> --- a/exec.c >> +++ b/exec.c >> @@ -411,6 +411,36 @@ address_space_translate_internal(AddressSpaceDispatch *d, hwaddr addr, hwaddr *x >> } >> >> /* Called from RCU critical section */ >> +IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr, >> + bool is_write) >> +{ >> + IOMMUTLBEntry iotlb = {0}; >> + MemoryRegionSection *section; >> + MemoryRegion *mr; >> + hwaddr plen; >> + >> + for (;;) { >> + AddressSpaceDispatch *d = atomic_rcu_read(&as->dispatch); >> + section = address_space_translate_internal(d, addr, &addr, &plen, true); >> + mr = section->mr; >> + >> + if (!mr->iommu_ops) { >> + break; >> + } >> + >> + iotlb = mr->iommu_ops->translate(mr, addr, is_write); >> + if (!(iotlb.perm & (1 << is_write))) { >> + iotlb.target_as = NULL; >> + break; >> + } > Here, do we still need something like: > > addr = ((iotlb.translated_addr & ~iotlb.addr_mask) > | (addr & iotlb.addr_mask)); > > Just as address_space_translate() does? Now "addr" should be the > offset in memory region "mr", while we need it to be the offset in > address space if there are more loops, right? Right, will address this in next version. > > Also, not sure whether we can abstract a shared function out of this > function and address_space_translate(). Looks possible. Thanks > > Thanks. > > -- peterx >