From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>,
Keir Fraser <keir@xen.org>, Tim Deegan <tim@xen.org>
Subject: Re: [PATCH] x86/HVM: refuse doing string operations in certain situations
Date: Fri, 20 Sep 2013 16:05:15 -0400 [thread overview]
Message-ID: <20130920200515.GQ5707@phenom.dumpdata.com> (raw)
In-Reply-To: <523C64FD02000078000F4EF1@nat28.tlf.novell.com>
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 <jbeulich@suse.com>
>
> --- 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 <jbeulich@suse.com>
>
> --- 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
next prev parent reply other threads:[~2013-09-20 20:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-20 13:08 [PATCH] x86/HVM: refuse doing string operations in certain situations Jan Beulich
2013-09-20 15:30 ` Keir Fraser
2013-09-20 20:05 ` Konrad Rzeszutek Wilk [this message]
2013-09-23 6:44 ` Jan Beulich
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