On 8/15/07, Chris Wright <[email protected]> wrote:
> * Glauber de Oliveira Costa ([email protected]) wrote:
> > Only caveat, is that it has to be done before smp gets in the game, and
> > with interrupts disabled. (which makes the function in vsmp.c not eligible).
> >
> > My current option is to force VSMP to use PARAVIRT, as said before, and
> > then fill paravirt_arch_setup, which is currently unused, with code to
> > replace the needed paravirt_ops.fn.
> >
> > I don't know if there is any method to dynamically determine (at this
> > point) that we are in a vsmp arch, and if there are not, it will have to
> > get ifdefs anyway. But at least, they are far more local.
>
> between __cacheline_aligned_in_smp and other compile time bits based on
> VSMP specific INTERNODE_CACHE, etc. I think compile time the way to go.
>
> > I am okay with both, but after all the explanation, I don't think that
> > adding a new pvops is a bad idea. It would make things less cumbersome
> > in this case. Also, hacks like this save_fl may require changes to the
> > hypervisor, right? I don't even know where such hypervisor is, and how
> > easy it is to replace it (it may be deeply hidden in firmware)
>
> No hypervisor change needed. Just the pv backend needs to return 0 or
> X86_EFLAGS_IF for save_flags (and similar translation on restore_flags).
> Xen uses a simple shared memory flag and does something which you could
> roughly translate into this:
>
> xen_save_flags()
> if (xen_vcpu_interrupts_enabled)
> return X86_EFLAGS_IF;
> else
> return 0;
>
> This doesn't require any hypervisor changes. Similarly, VSMP could do
> something along the lines of:
>
> vsmp_save_flags()
> flags = native_save_flags();
> if (flags & X86_EFLAGS_IF) || (flags & X86_EFLAGS_AC)
> return X86_EFLAGS_IF;
> else
> return 0;
>
I'm attaching to this message my idea on how would it work.
This is just for comments/considerations. If you all ack this, I'll
spread the changes over the patch series as needed, and then resend
the patches.
--
Glauber de Oliveira Costa.
"Free as in Freedom"
http://glommer.net
"The less confident you are, the more serious you have to act."
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index 00b2fc9..1204b08 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -150,6 +150,7 @@ config X86_PC
config X86_VSMP
bool "Support for ScaleMP vSMP"
depends on PCI
+ select PARAVIRT
help
Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
supposed to run on these EM64T-based machines. Only choose this option
diff --git a/arch/x86_64/kernel/paravirt.c b/arch/x86_64/kernel/paravirt.c
index dcd9919..23a8786 100644
--- a/arch/x86_64/kernel/paravirt.c
+++ b/arch/x86_64/kernel/paravirt.c
@@ -22,6 +22,8 @@
#include <linux/efi.h>
#include <linux/bcd.h>
#include <linux/start_kernel.h>
+#include <linux/pci_regs.h>
+#include <linux/pci_ids.h>
#include <asm/bug.h>
#include <asm/paravirt.h>
@@ -40,15 +42,30 @@
#include <asm/asm-offsets.h>
#include <asm/smp.h>
#include <asm/irqflags.h>
+#include <asm/pci-direct.h>
/* nop stub */
void _paravirt_nop(void)
{
}
+int arch_is_vsmp = 0;
+
/* natively, we do normal setup, but we still need to return something */
static int native_arch_setup(void)
{
+ if (!early_pci_allowed())
+ goto out;
+
+ if ((read_pci_config_16(0, 0x1f, 0, PCI_VENDOR_ID) == PCI_VENDOR_ID_SCALEMP) &&
+ (read_pci_config_16(0, 0x1f, 0, PCI_DEVICE_ID) == PCI_DEVICE_ID_SCALEMP_VSMP_CTL)) {
+ paravirt_ops.irq_disable = vsmp_irq_disable;
+ paravirt_ops.irq_enable = vsmp_irq_enable;
+ paravirt_ops.save_fl = vsmp_save_flags;
+ arch_is_vsmp = 1;
+ }
+
+out:
return 0;
}
@@ -103,8 +120,6 @@ static unsigned native_patch(u8 type, u16 clobbers, void *insns, unsigned len)
switch(type) {
#define SITE(x) case PARAVIRT_PATCH(x): start = start_##x; end = end_##x; goto patch_site
- SITE(irq_disable);
- SITE(irq_enable);
SITE(restore_fl);
SITE(save_fl);
SITE(iret);
@@ -117,7 +132,23 @@ static unsigned native_patch(u8 type, u16 clobbers, void *insns, unsigned len)
SITE(flush_tlb_single);
SITE(wbinvd);
#undef SITE
-
+ case PARAVIRT_PATCH(irq_disable):
+ case PARAVIRT_PATCH(irq_enable):
+ start = start_irq_disable;
+ end = end_irq_disable;
+
+ if (type == PARAVIRT_PATCH(irq_enable)) {
+ start = start_irq_enable;
+ end = end_irq_enable;
+ }
+
+ if (arch_is_vsmp) {
+ ret = paravirt_patch_default(type,
+ clobbers,
+ insns,
+ len);
+ break;
+ }
patch_site:
ret = paravirt_patch_insns(insns, len, start, end);
break;
@@ -214,30 +245,6 @@ void init_IRQ(void)
paravirt_ops.init_IRQ();
}
-static unsigned long native_save_fl(void)
-{
- unsigned long f;
- asm volatile("pushfq ; popq %0":"=g" (f): /* no input */);
- return f;
-}
-
-static void native_restore_fl(unsigned long f)
-{
- asm volatile("pushq %0 ; popfq": /* no output */
- :"g" (f)
- :"memory", "cc");
-}
-
-static void native_irq_disable(void)
-{
- asm volatile("cli": : :"memory");
-}
-
-static void native_irq_enable(void)
-{
- asm volatile("sti": : :"memory");
-}
-
static void native_io_delay(void)
{
asm volatile("outb %al,$0x80");
@@ -328,8 +328,8 @@ struct paravirt_ops paravirt_ops = {
.write_cr3 = native_write_cr3,
.read_cr4 = native_read_cr4,
.write_cr4 = native_write_cr4,
- .save_fl = native_save_fl,
- .restore_fl = native_restore_fl,
+ .save_fl = native_save_flags,
+ .restore_fl = native_restore_flags,
.irq_disable = native_irq_disable,
.irq_enable = native_irq_enable,
.safe_halt = native_raw_safe_halt,
diff --git a/arch/x86_64/kernel/vsmp.c b/arch/x86_64/kernel/vsmp.c
index 414caf0..ddfb1b7 100644
--- a/arch/x86_64/kernel/vsmp.c
+++ b/arch/x86_64/kernel/vsmp.c
@@ -15,6 +15,7 @@
#include <linux/pci_regs.h>
#include <asm/pci-direct.h>
#include <asm/io.h>
+#include <asm/irqflags.h>
static int __init vsmp_init(void)
{
diff --git a/include/asm-x86_64/irqflags.h b/include/asm-x86_64/irqflags.h
index fe0d346..eb993f4 100644
--- a/include/asm-x86_64/irqflags.h
+++ b/include/asm-x86_64/irqflags.h
@@ -16,11 +16,7 @@
* Interrupt control:
*/
-#ifdef CONFIG_PARAVIRT
-#include <asm/paravirt.h>
-#else /* PARAVIRT */
-
-static inline unsigned long __raw_local_save_flags(void)
+static inline unsigned long native_save_flags(void)
{
unsigned long flags;
@@ -35,7 +31,7 @@ static inline unsigned long __raw_local_save_flags(void)
return flags;
}
-static inline void raw_local_irq_restore(unsigned long flags)
+static inline void native_restore_flags(unsigned long flags)
{
__asm__ __volatile__(
"pushq %0 ; popfq"
@@ -45,57 +41,59 @@ static inline void raw_local_irq_restore(unsigned long flags)
);
}
-#ifdef CONFIG_X86_VSMP
+static inline void native_irq_disable(void)
+{
+ __asm__ __volatile__("cli" : : : "memory");
+}
+
+static inline void native_irq_enable(void)
+{
+ __asm__ __volatile__("sti" : : : "memory");
+}
+
+static inline long raw_irqs_disabled_flags(unsigned long flags)
+{
+ return !(flags & X86_EFLAGS_IF);
+}
/*
* Interrupt control for the VSMP architecture:
*/
-static inline void raw_local_irq_disable(void)
+static inline unsigned long vsmp_save_flags(void)
{
- unsigned long flags = __raw_local_save_flags();
+ unsigned long flags = vsmp_save_flags();
- raw_local_irq_restore((flags & ~X86_EFLAGS_IF) | X86_EFLAGS_AC);
+ if ((flags & X86_EFLAGS_IF) || (flags & X86_EFLAGS_AC))
+ return X86_EFLAGS_IF;
+ return 0;
}
-static inline void raw_local_irq_enable(void)
+static inline void vsmp_irq_disable(void)
{
unsigned long flags = __raw_local_save_flags();
- raw_local_irq_restore((flags | X86_EFLAGS_IF) & (~X86_EFLAGS_AC));
+ raw_local_irq_restore((flags & ~X86_EFLAGS_IF) | X86_EFLAGS_AC);
}
-#else /* CONFIG_X86_VSMP */
-
-static inline void raw_local_irq_disable(void)
+static inline void vsmp_irq_enable(void)
{
- __asm__ __volatile__("cli" : : : "memory");
-}
+ unsigned long flags = __raw_local_save_flags();
-static inline void raw_local_irq_enable(void)
-{
- __asm__ __volatile__("sti" : : : "memory");
+ raw_local_irq_restore((flags | X86_EFLAGS_IF) & (~X86_EFLAGS_AC));
}
-#endif /* CONFIG_X86_VSMP */
-#endif /* CONFIG_PARAVIRT */
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+#else /* PARAVIRT */
+#define __raw_local_save_flags() native_save_flags()
+#define raw_local_irq_restore(x) native_restore_flags(x)
+#define raw_local_irq_disable() native_irq_disable()
+#define raw_local_irq_enable() native_irq_enable()
+#endif
/* Those are not paravirt stubs, so they live out of the PARAVIRT ifdef */
-#ifdef CONFIG_X86_VSMP
-static inline int raw_irqs_disabled_flags(unsigned long flags)
-{
- return !(flags & X86_EFLAGS_IF) || (flags & X86_EFLAGS_AC);
-}
-
-#else
-static inline int raw_irqs_disabled_flags(unsigned long flags)
-{
- return !(flags & X86_EFLAGS_IF);
-}
-
-#endif /* CONFIG_X86_VSMP */
-
#define raw_local_save_flags(flags) \
do { (flags) = __raw_local_save_flags(); } while (0)
/*
diff --git a/include/asm-x86_64/paravirt.h b/include/asm-x86_64/paravirt.h
diff --git a/include/asm-x86_64/processor.h b/include/asm-x86_64/processor.h
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