[PATCH v4 7/8] tools/xl: enable NS16550-compatible UART emulator for PVH (x86)

[dmkhn@xxxxxxxxx]

From: Denis Mukhin <dmukhin@xxxxxxxx> 

Enable virtual NS16550 for PVH domains in xl.

{map,unmap}_domain_emuirq_pirq() infrastructure is modified by adding new
type of interrupt resources 'IRQ_EMU' which means 'emulated device IRQ'
(similarly to IRQ_MSI_EMU).

This is necessary to for IOAPIC emulation code to skip IRQ->PIRQ mapping
(vioapic_hwdom_map_gsi()) when guest OS unmasks vIOAPIC pin corresponding to
virtual device's IRQ.

Also, hvm_gsi_eoi() is modified to trigger assertion in hvm_gsi_deassert()
path for ISA IRQs.

Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
Changes since v3:
- new patch
---
 tools/libs/light/libxl_x86.c          |  2 +-
 xen/arch/x86/domain.c                 |  2 ++
 xen/arch/x86/hvm/vioapic.c            | 10 ++++++++++
 xen/arch/x86/include/asm/irq.h        |  1 +
 xen/common/emul/vuart/vuart-ns16550.c | 27 +++++++++++++++++++++++++--
 xen/drivers/passthrough/x86/hvm.c     |  9 ++++-----
 6 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/tools/libs/light/libxl_x86.c b/tools/libs/light/libxl_x86.c
index 0f039ca65a88..a40647c06cb9 100644
--- a/tools/libs/light/libxl_x86.c
+++ b/tools/libs/light/libxl_x86.c
@@ -54,7 +54,7 @@ int libxl__arch_domain_prepare_config(libxl__gc *gc,
         break;
     case LIBXL_DOMAIN_TYPE_PVH:
         config->arch.emulation_flags = XEN_X86_EMU_LAPIC;
-        libxl__arch_domain_vuart_unsupported(gc, d_config, config);
+        libxl__arch_domain_vuart_enable(gc, d_config, config);
         break;
     case LIBXL_DOMAIN_TYPE_PV:
         config->arch.emulation_flags = 0;
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 6a010a509a60..39b0c0b199b9 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -769,12 +769,14 @@ static bool emulation_flags_ok(const struct domain *d, 
uint32_t emflags)
         {
             .caps   = CAP_HVM | CAP_HWDOM,
             .min    = X86_EMU_LAPIC | X86_EMU_IOAPIC | X86_EMU_VPCI,
+            .opt    = X86_EMU_NS16550,
         },
 
         /* PVH domU */
         {
             .caps   = CAP_HVM | CAP_DOMU,
             .min    = X86_EMU_LAPIC,
+            .opt    = X86_EMU_NS16550,
         },
 
         /* HVM domU */
diff --git a/xen/arch/x86/hvm/vioapic.c b/xen/arch/x86/hvm/vioapic.c
index 7c725f9e471f..86fe3aa4a201 100644
--- a/xen/arch/x86/hvm/vioapic.c
+++ b/xen/arch/x86/hvm/vioapic.c
@@ -177,6 +177,16 @@ static int vioapic_hwdom_map_gsi(unsigned int gsi, 
unsigned int trig,
 
     ASSERT(is_hardware_domain(currd));
 
+    /*
+     * Interrupt is claimed by one of the platform virtual devices (e.g.
+     * NS16550); do nothing.
+     */
+    read_lock(&currd->event_lock);
+    ret = domain_pirq_to_emuirq(currd, gsi);
+    read_unlock(&currd->event_lock);
+    if ( ret != IRQ_UNBOUND )
+        return 0;
+
     /* Interrupt has been unmasked, bind it now. */
     ret = mp_register_gsi(gsi, trig, pol);
     if ( ret == -EEXIST )
diff --git a/xen/arch/x86/include/asm/irq.h b/xen/arch/x86/include/asm/irq.h
index 8c81f66434a8..731d2bbbb1b4 100644
--- a/xen/arch/x86/include/asm/irq.h
+++ b/xen/arch/x86/include/asm/irq.h
@@ -221,6 +221,7 @@ void cleanup_domain_irq_mapping(struct domain *d);
 #define IRQ_UNBOUND (-1)
 #define IRQ_PT      (-2)
 #define IRQ_MSI_EMU (-3)
+#define IRQ_EMU     (-4)
 
 bool cpu_has_pending_apic_eoi(void);
 
diff --git a/xen/common/emul/vuart/vuart-ns16550.c 
b/xen/common/emul/vuart/vuart-ns16550.c
index 48bbf58264fe..9ec9aed2c594 100644
--- a/xen/common/emul/vuart/vuart-ns16550.c
+++ b/xen/common/emul/vuart/vuart-ns16550.c
@@ -355,7 +355,9 @@ static void ns16550_irq_assert(const struct vuart_ns16550 
*vdev)
     struct domain *d = vdev->owner;
     int vector;
 
-    if ( has_vpic(d) ) /* HVM */
+    if ( has_vioapic(d) && !has_vpic(d) ) /* PVH */
+        vector = hvm_ioapic_assert(d, vdev->irq, false);
+    else if ( has_vpic(d) ) /* HVM */
         vector = hvm_isa_irq_assert(d, vdev->irq, vioapic_get_vector);
     else
         ASSERT_UNREACHABLE();
@@ -367,7 +369,9 @@ static void ns16550_irq_deassert(const struct vuart_ns16550 
*vdev)
 {
     struct domain *d = vdev->owner;
 
-    if ( has_vpic(d) ) /* HVM */
+    if ( has_vioapic(d) && !has_vpic(d) ) /* PVH */
+        hvm_ioapic_deassert(d, vdev->irq);
+    else if ( has_vpic(d) ) /* HVM */
         hvm_isa_irq_deassert(d, vdev->irq);
     else
         ASSERT_UNREACHABLE();
@@ -889,6 +893,17 @@ static int cf_check ns16550_init(struct domain *d,
                 return rc;
             }
 
+            /* Claim virtual IRQ */
+            write_lock(&d->event_lock);
+            rc = map_domain_emuirq_pirq(d, r->addr, IRQ_EMU);
+            write_unlock(&d->event_lock);
+            if ( rc )
+            {
+                pr_err("%s: virtual IRQ#%"PRIu64": cannot claim: %d\n",
+                        desc->name, r->addr, rc);
+                return rc;
+            }
+
             vdev->irq = r->addr;
         }
         else
@@ -919,12 +934,20 @@ static int cf_check ns16550_init(struct domain *d,
 static void cf_check ns16550_deinit(struct domain *d)
 {
     struct vuart_ns16550 *vdev = d->arch.hvm.vuart;
+    int rc;
 
     if ( !vdev )
         return;
 
     spin_lock(&vdev->lock);
 
+    rc = unmap_domain_pirq_emuirq(vdev->owner, vdev->irq);
+    if ( rc )
+    {
+        pr_err("%s: virtual IRQ#%d: cannot unclaim: %d\n",
+                vdev->name, vdev->irq, rc);
+    }
+
     ns16550_fifo_tx_flush(vdev);
 
     spin_unlock(&vdev->lock);
diff --git a/xen/drivers/passthrough/x86/hvm.c 
b/xen/drivers/passthrough/x86/hvm.c
index a2ca7e0e570c..22905cd86f95 100644
--- a/xen/drivers/passthrough/x86/hvm.c
+++ b/xen/drivers/passthrough/x86/hvm.c
@@ -924,12 +924,11 @@ static void hvm_gsi_eoi(struct domain *d, unsigned int 
gsi)
 {
     struct pirq *pirq = pirq_info(d, gsi);
 
-    /* Check if GSI is actually mapped. */
-    if ( !pirq_dpci(pirq) )
-        return;
-
     hvm_gsi_deassert(d, gsi);
-    hvm_pirq_eoi(pirq);
+
+    /* Check if GSI is actually mapped. */
+    if ( pirq_dpci(pirq) )
+        hvm_pirq_eoi(pirq);
 }
 
 static int cf_check _hvm_dpci_isairq_eoi(
-- 
2.34.1