[Xen-devel] [RFC PATCH v2 12/17] xenconsoled: make console_type->use_gnttab less confusing

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

Before this commit 'use_gnttab' means xenconsoled should first try
special GNTTAB_RESERVED_CONSOLE entry, and only then fallback to
ring-ref xenstore entry (being gfn of actual ring).
In case of secondary consoles, ring-ref entry contains grant table
reference (not gfn of it), which makes the old meaning of use_gnttab
really confusing (should be false for such consoles).
To solve this, add new entry in console_type (and console) structures
named 'use_reserverd_gnttab' with the old meaning of 'use_gnttab', then
use 'ues_gnttab' for consoles where ring-ref holds grant table
reference.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
 tools/console/daemon/io.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/tools/console/daemon/io.c b/tools/console/daemon/io.c
index 82806b2..3f2b9cb 100644
--- a/tools/console/daemon/io.c
+++ b/tools/console/daemon/io.c
@@ -111,6 +111,7 @@ struct console {
        struct domain *d;
        bool optional;
        bool use_gnttab;
+       bool use_reserved_gnttab;
        bool have_state;
 };
 
@@ -120,6 +121,7 @@ struct console_type {
        char *log_suffix;
        bool optional;
        bool use_gnttab;
+       bool use_reserved_gnttab;
        bool have_state;  // uses 'state' xenstore entry
 };
 
@@ -130,6 +132,7 @@ static struct console_type console_type[] = {
                .log_suffix = "",
                .optional = false,
                .use_gnttab = true,
+               .use_reserved_gnttab = true,
        },
 #if defined(CONFIG_ARM)
        {
@@ -695,7 +698,7 @@ static void console_unmap_interface(struct console *con)
 {
        if (con->interface == NULL)
                return;
-       if (xgt_handle && con->ring_ref == -1)
+       if (xgt_handle && con->use_gnttab)
                xengnttab_unmap(xgt_handle, con->interface, 1);
        else
                munmap(con->interface, XC_PAGE_SIZE);
@@ -739,12 +742,19 @@ static int console_create_ring(struct console *con)
 
        if (!con->interface && xgt_handle && con->use_gnttab) {
                /* Prefer using grant table */
-               con->interface = xengnttab_map_grant_ref(xgt_handle,
-                       dom->domid, GNTTAB_RESERVED_CONSOLE,
-                       PROT_READ|PROT_WRITE);
-               con->ring_ref = -1;
+               if (con->use_reserved_gnttab) {
+                       con->interface = xengnttab_map_grant_ref(xgt_handle,
+                                       dom->domid, GNTTAB_RESERVED_CONSOLE,
+                                       PROT_READ|PROT_WRITE);
+                       con->ring_ref = -1;
+               } else {
+                       con->interface = xengnttab_map_grant_ref(xgt_handle,
+                                       dom->domid, ring_ref,
+                                       PROT_READ|PROT_WRITE);
+                       con->ring_ref = ring_ref;
+               }
        }
-       if (!con->interface) {
+       if (!con->interface && (!con->use_gnttab || con->use_reserved_gnttab)) {
                /* Fall back to xc_map_foreign_range */
                con->interface = xc_map_foreign_range(
                        xc, dom->domid, XC_PAGE_SIZE,
@@ -918,6 +928,7 @@ static int console_init(struct console *con, struct domain 
*dom, void **data)
        con->log_suffix = (*con_type)->log_suffix;
        con->optional = (*con_type)->optional;
        con->use_gnttab = (*con_type)->use_gnttab;
+       con->use_reserved_gnttab = (*con_type)->use_reserved_gnttab;
        con->have_state = (*con_type)->have_state;
        xsname = (char *)(*con_type)->xsname;
        xspath = xs_get_domain_path(xs, dom->domid);
-- 
git-series 0.9.1

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