kvm tools, bios: Make sure IRQ handlers segment is properly set

The mini bios is copied at predefined place and should have
constant segment address.

Without this patch cs value varies depending on which code
is compiled and how big bios is, it's kinda flowing error
which is not triggered yet by a pure luck.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/tools/kvm/bios.c b/tools/kvm/bios.c
index 94e914cc1740db0fa40a2e341d6aff8de4afd5ff..6aefd1bdc19b5f26745b8d4488f5c04262b27770 100644 (file)
--- a/tools/kvm/bios.c
+++ b/tools/kvm/bios.c
@@ -16,14 +16,14 @@ struct irq_handler {
        size_t                  size;
 };
 
-#define BIOS_IRQ_ADDR(name) (MB_BIOS_BEGIN + BIOS_OFFSET__##name)
-#define BIOS_IRQ_FUNC(name) ((char *)&bios_rom[BIOS_OFFSET__##name])
-#define BIOS_IRQ_SIZE(name) (BIOS_ENTRY_SIZE(BIOS_OFFSET__##name))
+#define BIOS_IRQ_PA_ADDR(name) (MB_BIOS_BEGIN + BIOS_OFFSET__##name)
+#define BIOS_IRQ_FUNC(name)    ((char *)&bios_rom[BIOS_OFFSET__##name])
+#define BIOS_IRQ_SIZE(name)    (BIOS_ENTRY_SIZE(BIOS_OFFSET__##name))
 
 #define DEFINE_BIOS_IRQ_HANDLER(_irq, _handler)                        \
        {                                                       \
                .irq            = _irq,                         \
-               .address        = BIOS_IRQ_ADDR(_handler),      \
+               .address        = BIOS_IRQ_PA_ADDR(_handler),   \
                .handler        = BIOS_IRQ_FUNC(_handler),      \
                .size           = BIOS_IRQ_SIZE(_handler),      \
        }
@@ -42,10 +42,12 @@ static void setup_irq_handler(struct kvm *kvm, struct irq_handler *handler)
        memcpy(p, handler->handler, handler->size);
 
        intr_desc = (struct real_intr_desc) {
-               .segment        = REAL_SEGMENT(handler->address),
-               .offset         = REAL_OFFSET(handler->address),
+               .segment        = REAL_SEGMENT(MB_BIOS_BEGIN),
+               .offset         = handler->address - MB_BIOS_BEGIN,
        };
 
+       DIE_IF((handler->address - MB_BIOS_BEGIN) > (unsigned long)0xffff);
+
        interrupt_table__set(&kvm->interrupt_table, &intr_desc, handler->irq);
 }
 
@@ -139,10 +141,10 @@ void setup_bios(struct kvm *kvm)
         * Setup a *fake* real mode vector table, it has only
         * one real hadler which does just iret
         */
-       address = BIOS_IRQ_ADDR(bios_intfake);
+       address = BIOS_IRQ_PA_ADDR(bios_intfake);
        intr_desc = (struct real_intr_desc) {
-               .segment        = REAL_SEGMENT(address),
-               .offset         = REAL_OFFSET(address),
+               .segment        = REAL_SEGMENT(MB_BIOS_BEGIN),
+               .offset         = address - MB_BIOS_BEGIN,
        };
        interrupt_table__setup(&kvm->interrupt_table, &intr_desc);