cmdline: "extra_guest_irqs" is inapplicable to PVH

PVH in particular has no (externally visible) notion of pIRQ-s. Mention
that in the description of the respective command line option and have
arch_hwdom_irqs() also reflect this (thus suppressing the log message
there as well, as being pretty meaningless in this case anyway).

Suggested-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>

diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc
index cd9a7164f4b09dc1096aedc36029ffbc986baad6..98a45211556b7acda227df1a8d23155db6a31278 100644 (file)
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -1178,7 +1178,8 @@ versa.  For example to change dom0 without changing domU, use
 hardware domain is architecture dependent.  The upper limit for both values on
 x86 is such that the resulting total number of IRQs can't be higher than 32768.
 Note that specifying zero as domU value means zero, while for dom0 it means
-to use the default.
+to use the default.  Note further that the Dom0 setting has no useful meaning
+for the PVH case; use of the option may have an adverse effect there, though.
 
 ### ext_regions (Arm)
 > `= <boolean>`

diff --git a/xen/arch/x86/io_apic.c b/xen/arch/x86/io_apic.c
index d2b29143d159ee1e4547dfa66b27593b25d6a77f..d2a313c4ac72ebe1e0dfe2e1d2c1c14e5406bbe3 100644 (file)
--- a/xen/arch/x86/io_apic.c
+++ b/xen/arch/x86/io_apic.c
@@ -2670,6 +2670,10 @@ unsigned int __hwdom_init arch_hwdom_irqs(const struct domain *d)
     if ( is_system_domain(d) )
         return max_irqs;
 
+    /* PVH (generally: HVM) can't use PHYSDEVOP_pirq_eoi_gmfn_v{1,2}. */
+    if ( is_hvm_domain(d) )
+        return nr_irqs;
+
     if ( !d->domain_id )
         n = min(n, dom0_max_vcpus());
     n = min(nr_irqs_gsi + n * NR_DYNAMIC_VECTORS, max_irqs);