[RFC PATCH v1] powerpc/XIVE: SVM: share the event-queue page with the Hypervisor.

[Ram Pai]

XIVE interrupt controller maintains a Event-Queue(EQ) page. This page is
used to communicate events with the Hypervisor/Qemu. In Secure-VM,
unless a page is shared with the Hypervisor, the Hypervisor will
not be able to read/write to that page.

Explicitly share the EQ page with the Hypervisor, and unshare it
during cleanup.  This enables SVM to use XIVE.

(NOTE: If the Hypervisor/Ultravisor is unable to target interrupts
 directly to Secure VM, use "kernel_irqchip=off" on the qemu command
 line).

Cc: kvm-ppc at vger.kernel.org
Cc: linuxppc-dev at lists.ozlabs.org
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Thiago Jung Bauermann <bauerman at linux.ibm.com>
Cc: Michael Anderson <andmike at linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
Cc: Alexey Kardashevskiy <aik at ozlabs.ru>
Cc: Paul Mackerras <paulus at ozlabs.org>
Cc: Greg Kurz <groug at kaod.org>
Cc: Cedric Le Goater <clg at fr.ibm.com>
Cc: David Gibson <david at gibson.dropbear.id.au>
Signed-off-by: Ram Pai <linuxram at us.ibm.com>
---
 arch/powerpc/sysdev/xive/spapr.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/sysdev/xive/spapr.c b/arch/powerpc/sysdev/xive/spapr.c
index 55dc61c..608b52f 100644
--- a/arch/powerpc/sysdev/xive/spapr.c
+++ b/arch/powerpc/sysdev/xive/spapr.c
@@ -26,6 +26,8 @@
 #include <asm/xive.h>
 #include <asm/xive-regs.h>
 #include <asm/hvcall.h>
+#include <asm/svm.h>
+#include <asm/ultravisor.h>
 
 #include "xive-internal.h"
 
@@ -501,6 +503,9 @@ static int xive_spapr_configure_queue(u32 target, struct xive_q *q, u8 prio,
 		rc = -EIO;
 	} else {
 		q->qpage = qpage;
+		if (is_secure_guest())
+			uv_share_page(PHYS_PFN(qpage_phys),
+					1 << xive_alloc_order(order));
 	}
 fail:
 	return rc;
@@ -534,6 +539,8 @@ static void xive_spapr_cleanup_queue(unsigned int cpu, struct xive_cpu *xc,
 		       hw_cpu, prio);
 
 	alloc_order = xive_alloc_order(xive_queue_shift);
+	if (is_secure_guest())
+		uv_unshare_page(PHYS_PFN(__pa(q->qpage)), 1 << alloc_order);
 	free_pages((unsigned long)q->qpage, alloc_order);
 	q->qpage = NULL;
 }
-- 
1.8.3.1