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Message-ID: <20130820193507.GI12037@phenom.dumpdata.com>
Date: Tue, 20 Aug 2013 15:35:07 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Ian Campbell <ian.campbell@...rix.com>
Cc: xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: Re: [Xen-devel] [PATCH] xen/hvc: If we use xen_raw_printk let it
also work on HVM guests.
On Thu, Aug 15, 2013 at 03:40:38PM +0100, Ian Campbell wrote:
> On Wed, 2013-08-14 at 08:46 -0400, Konrad Rzeszutek Wilk wrote:
> > On Wed, Aug 14, 2013 at 08:15:56AM +0100, Ian Campbell wrote:
> > > On Tue, 2013-08-13 at 20:10 -0400, Konrad Rzeszutek Wilk wrote:
> > > > On Tue, Aug 13, 2013 at 11:20:05PM +0100, Ian Campbell wrote:
> > > > > On Tue, 2013-08-13 at 21:59 +0100, Ian Campbell wrote:
> > > > >
> > > > > > > What it should be is:
> > > > > > > > >
> > > > > > > > > void xen_raw_console_write(const char *str)
> > > > > > > > > {
> > > > > > > > > - dom0_write_console(0, str, strlen(str));
> > > > > > > > > + if (!xen_domain())
> > > > > > > > > + return;
> > > > > > > > > +
> > > > > > > > > + if (xen_pv_domain())
> > > > > > > xen_domain()
> > > > > > >
> > > > > > > > > + dom0_write_console(0, str, strlen(str));
> > > > > > > > > + else if (xen_hvm_domain() || xen_cpuid_base()) {
> > > > > > >
> > > > > > > else if (xen_cpuid_base()) {
> > > > > > >
> > > > > > > > > + /* The hyperpage has not been setup yet. */
> > > > > > > > > + int i, len = strlen(str);
> > > > > > > > > + for (i = 0; i < len; i++)
> > > > > > > > > + outb(str[i], 0xe9);
> > > > > > > > > + }
> > > > > > > > > }
> > > > > > >
> > > > > > > And then that should adhere to what I wrote up.
> > > > > >
> > > > > > I think it does too.
> > > > >
> > > > > Except as Daniel notes in <520A7145.5010306@...ho.nsa.gov> for unrelated
> > > > > reasons:
> > > > >
> > > > > > HVM guests can still use the PV output - they just need to use the console
> > > > > > write hypercall instead of the HVM I/O port. I would think that PVH guests
> > > > > > would default to using the hypercall as it is more efficient (it takes a
> > > > > > string rather than one character per write).
> > > > > >
> > > > > > Actually, checking... the console_io hypercall would need to be added to
> > > > > > the hvm_hypercall{32,64}_table for an HVM guest to be able to use it; they
> > > > > > currently must use the I/O port. I didn't check the PVH patches.
> > > > >
> > > > > Or did you actually try this code and it worked?
> > > >
> > > > The one I typed up above - no. The one I had sent - yes.
> > > >
> > > > But with that above mentioned comment from Daniel I think it is still
> > > > worth trying to do dom0_write_console and if the hypercall returns -ENOSYS
> > > > then fall back on 0xe9.
> > > >
> > > > And lastly send an patch to make hypercall_io work under HVM.
> > >
> > > So you didn't try under PVHVM? That's what I was asking when I asked if
> > > you tried it, since that is the point of this patch.
> >
> > Not the one I typed up above. Just the one I sent.
>
> And did it work? ecause if the console_io hypercall isn't wired up in
> the hypervisor I can't see how it can have done...
>
> Oh the original patch would buggily never have tried to use console_io,
> and you probably didn't notice the lack of output after the hypercall
> page was setup.
<nods>
This is a patch below that works for me and also it work with hypervisors
that don't have console_io wired in.
Pls treat it as RFC
>From 5b5faae0038d48aa0169bab8c78d1b47c4f1ac64 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Date: Fri, 16 Aug 2013 15:32:07 -0400
Subject: [PATCH] xen/hvc: Print out to the serial console and pv console
irregardless if it is dom0, PV or HVM.
*TODO*: BLA BLA BLA
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
drivers/tty/hvc/hvc_xen.c | 15 ++++++++++++++-
1 files changed, 14 insertions(+), 1 deletions(-)
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 682210d..e47c6ae 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -40,6 +40,7 @@
#include <xen/hvc-console.h>
#include <xen/xenbus.h>
+#include <asm/xen/hypervisor.h>
#include "hvc_console.h"
#define HVC_COOKIE 0x58656e /* "Xen" in hex */
@@ -641,7 +642,19 @@ struct console xenboot_console = {
void xen_raw_console_write(const char *str)
{
- dom0_write_console(0, str, strlen(str));
+ ssize_t len = strlen(str);
+ int rc = 0;
+
+ if (xen_domain()) {
+ rc = dom0_write_console(0, str, len);
+ if (rc != len && xen_hvm_domain()) /* -ENOSYS */
+ goto outb_print;
+ } else if (xen_cpuid_base()) {
+ int i;
+outb_print:
+ for (i = 0; i < len; i++)
+ outb(str[i], 0xe9);
+ }
}
void xen_raw_printk(const char *fmt, ...)
--
1.7.7.6
> Ian.
>
--
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