From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH] x86/HVM: refuse doing string operations in certain situations Date: Fri, 20 Sep 2013 16:05:15 -0400 Message-ID: <20130920200515.GQ5707@phenom.dumpdata.com> References: <523C64FD02000078000F4EF1@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VN6x8-0007ro-Rq for xen-devel@lists.xenproject.org; Fri, 20 Sep 2013 20:05:23 +0000 Content-Disposition: inline In-Reply-To: <523C64FD02000078000F4EF1@nat28.tlf.novell.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: Jan Beulich Cc: xen-devel , Keir Fraser , Tim Deegan List-Id: xen-devel@lists.xenproject.org On Fri, Sep 20, 2013 at 02:08:45PM +0100, Jan Beulich wrote: > We shouldn't do any acceleration for > - "rep movs" when either side is passed through MMIO or when both sides > are handled by qemu > - "rep ins" and "rep outs" when the memory operand is any kind of MMIO Could you explain this in a bit more details? Why is acceleration in those cases bad? Thanks. > > Signed-off-by: Jan Beulich > > --- a/xen/arch/x86/hvm/emulate.c > +++ b/xen/arch/x86/hvm/emulate.c > @@ -686,6 +686,7 @@ static int hvmemul_rep_ins( > unsigned long addr; > uint32_t pfec = PFEC_page_present | PFEC_write_access; > paddr_t gpa; > + p2m_type_t p2mt; > int rc; > > rc = hvmemul_virtual_to_linear( > @@ -702,6 +703,10 @@ static int hvmemul_rep_ins( > if ( rc != X86EMUL_OKAY ) > return rc; > > + (void) get_gfn_query_unlocked(current->domain, gpa >> PAGE_SHIFT, &p2mt); > + if ( p2mt == p2m_mmio_direct || p2mt == p2m_mmio_dm ) > + return X86EMUL_UNHANDLEABLE; > + > return hvmemul_do_pio(src_port, reps, bytes_per_rep, gpa, IOREQ_READ, > !!(ctxt->regs->eflags & X86_EFLAGS_DF), NULL); > } > @@ -719,6 +724,7 @@ static int hvmemul_rep_outs( > unsigned long addr; > uint32_t pfec = PFEC_page_present; > paddr_t gpa; > + p2m_type_t p2mt; > int rc; > > rc = hvmemul_virtual_to_linear( > @@ -735,6 +741,10 @@ static int hvmemul_rep_outs( > if ( rc != X86EMUL_OKAY ) > return rc; > > + (void) get_gfn_query_unlocked(current->domain, gpa >> PAGE_SHIFT, &p2mt); > + if ( p2mt == p2m_mmio_direct || p2mt == p2m_mmio_dm ) > + return X86EMUL_UNHANDLEABLE; > + > return hvmemul_do_pio(dst_port, reps, bytes_per_rep, gpa, IOREQ_WRITE, > !!(ctxt->regs->eflags & X86_EFLAGS_DF), NULL); > } > @@ -787,6 +797,10 @@ static int hvmemul_rep_movs( > (void) get_gfn_query_unlocked(current->domain, sgpa >> PAGE_SHIFT, &sp2mt); > (void) get_gfn_query_unlocked(current->domain, dgpa >> PAGE_SHIFT, &dp2mt); > > + if ( sp2mt == p2m_mmio_direct || dp2mt == p2m_mmio_direct || > + (sp2mt == p2m_mmio_dm && dp2mt == p2m_mmio_dm) ) > + return X86EMUL_UNHANDLEABLE; > + > if ( sp2mt == p2m_mmio_dm ) > return hvmemul_do_mmio( > sgpa, reps, bytes_per_rep, dgpa, IOREQ_READ, df, NULL); > > > > x86/HVM: refuse doing string operations in certain situations > > We shouldn't do any acceleration for > - "rep movs" when either side is passed through MMIO or when both sides > are handled by qemu > - "rep ins" and "rep outs" when the memory operand is any kind of MMIO > > Signed-off-by: Jan Beulich > > --- a/xen/arch/x86/hvm/emulate.c > +++ b/xen/arch/x86/hvm/emulate.c > @@ -686,6 +686,7 @@ static int hvmemul_rep_ins( > unsigned long addr; > uint32_t pfec = PFEC_page_present | PFEC_write_access; > paddr_t gpa; > + p2m_type_t p2mt; > int rc; > > rc = hvmemul_virtual_to_linear( > @@ -702,6 +703,10 @@ static int hvmemul_rep_ins( > if ( rc != X86EMUL_OKAY ) > return rc; > > + (void) get_gfn_query_unlocked(current->domain, gpa >> PAGE_SHIFT, &p2mt); > + if ( p2mt == p2m_mmio_direct || p2mt == p2m_mmio_dm ) > + return X86EMUL_UNHANDLEABLE; > + > return hvmemul_do_pio(src_port, reps, bytes_per_rep, gpa, IOREQ_READ, > !!(ctxt->regs->eflags & X86_EFLAGS_DF), NULL); > } > @@ -719,6 +724,7 @@ static int hvmemul_rep_outs( > unsigned long addr; > uint32_t pfec = PFEC_page_present; > paddr_t gpa; > + p2m_type_t p2mt; > int rc; > > rc = hvmemul_virtual_to_linear( > @@ -735,6 +741,10 @@ static int hvmemul_rep_outs( > if ( rc != X86EMUL_OKAY ) > return rc; > > + (void) get_gfn_query_unlocked(current->domain, gpa >> PAGE_SHIFT, &p2mt); > + if ( p2mt == p2m_mmio_direct || p2mt == p2m_mmio_dm ) > + return X86EMUL_UNHANDLEABLE; > + > return hvmemul_do_pio(dst_port, reps, bytes_per_rep, gpa, IOREQ_WRITE, > !!(ctxt->regs->eflags & X86_EFLAGS_DF), NULL); > } > @@ -787,6 +797,10 @@ static int hvmemul_rep_movs( > (void) get_gfn_query_unlocked(current->domain, sgpa >> PAGE_SHIFT, &sp2mt); > (void) get_gfn_query_unlocked(current->domain, dgpa >> PAGE_SHIFT, &dp2mt); > > + if ( sp2mt == p2m_mmio_direct || dp2mt == p2m_mmio_direct || > + (sp2mt == p2m_mmio_dm && dp2mt == p2m_mmio_dm) ) > + return X86EMUL_UNHANDLEABLE; > + > if ( sp2mt == p2m_mmio_dm ) > return hvmemul_do_mmio( > sgpa, reps, bytes_per_rep, dgpa, IOREQ_READ, df, NULL); > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel