Re: [PATCH 4/7] xen/hvm: Xen PV extension of HVM initialization
From: Jeremy Fitzhardinge
Date: Thu Mar 04 2010 - 13:24:25 EST
On 03/04/2010 01:36 AM, Sheng Yang wrote:
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index b83e119..af3c7a0 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -36,3 +36,11 @@ config XEN_DEBUG_FS
help
Enable statistics output and various tuning options in debugfs.
Enabling this option may incur a significant performance overhead.
+
+config XEN_HVM_PV
+ bool "PV extension of HVM"
+ depends on XEN&& X86_64
+ default n
+ help
+ Enable the PV extension of HVM, so that HVM guest would benefit from
+ PV features like PV timer and evtchn.
Unless there's a strong reason to make this a user-visible setting, I'd
make it a hidden option which is enabled by default when the
dependencies are correct.
diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index 3bb4fc2..73bd5db 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -17,4 +17,5 @@ obj-y := enlighten.o setup.o multicalls.o mmu.o irq.o \
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
obj-$(CONFIG_XEN_DEBUG_FS) += debugfs.o
+obj-$(CONFIG_XEN_HVM_PV) += hvmpv.o
diff --git a/arch/x86/xen/hvmpv.c b/arch/x86/xen/hvmpv.c
new file mode 100644
index 0000000..7a741ed
--- /dev/null
+++ b/arch/x86/xen/hvmpv.c
@@ -0,0 +1,133 @@
+/*
+ * PV extension of HVM implementation.
+ *
+ * Sheng Yang<sheng@xxxxxxxxxxxxxxx>, Intel Corporation, 2010
+ *
+ */
+#include<linux/kernel.h>
+#include<linux/init.h>
+#include<linux/percpu.h>
+#include<linux/module.h>
+
+#include<xen/xen.h>
+#include<xen/features.h>
+#include<xen/events.h>
+#include<xen/hvm.h>
+#include<xen/interface/xen.h>
+#include<xen/interface/version.h>
+#include<xen/interface/memory.h>
+
+#include<asm/xen/cpuid.h>
+#include<asm/xen/hypercall.h>
+#include<asm/xen/hypervisor.h>
+
+#include "xen-ops.h"
+
+u32 xen_hvm_pv_features;
+EXPORT_SYMBOL_GPL(xen_hvm_pv_features);
+
+static const struct pv_info xen_hvm_pv_info __initdata = {
+ .paravirt_enabled = 1,
+ .shared_kernel_pmd = 0,
+ .kernel_rpl = 0,
+ .name = "Xen",
+};
+
+static void __init xen_hvm_pv_banner(void)
+{
+ unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
+ struct xen_extraversion extra;
+ HYPERVISOR_xen_version(XENVER_extraversion,&extra);
+
+ printk(KERN_INFO "Booting PV extended HVM kernel on %s\n",
+ pv_info.name);
+ printk(KERN_INFO "Xen version: %d.%d%s\n",
+ version>> 16, version& 0xffff, extra.extraversion);
+}
+
+static int __init xen_para_available(void)
+{
+ uint32_t eax, ebx, ecx, edx;
+ cpuid(XEN_CPUID_LEAF(0),&eax,&ebx,&ecx,&edx);
+
+ if (ebx == XEN_CPUID_SIGNATURE_EBX&&
+ ecx == XEN_CPUID_SIGNATURE_ECX&&
+ edx == XEN_CPUID_SIGNATURE_EDX&&
+ ((eax - XEN_CPUID_LEAF(0))>= 2))
+ return 1;
+
+ return 0;
+}
+
+static int __init enable_hvm_pv(u64 flags)
+{
+ struct xen_hvm_pv_type a;
+
+ a.domid = DOMID_SELF;
+ a.flags = flags;
+ return HYPERVISOR_hvm_op(HVMOP_enable_pv,&a);
+}
+
+static int __init init_hvm_pv_info(void)
+{
+ uint32_t ecx, edx, pages, msr;
+ u64 pfn;
+
+ if (!xen_para_available())
+ return -EINVAL;
+
+ cpuid(XEN_CPUID_LEAF(2),&pages,&msr,&ecx,&edx);
+
+ /* Check if hvm_pv mode is supported */
+ if (!(edx& XEN_CPUID_FEAT2_HVM_PV))
+ return -ENODEV;
+
+ /* We only support 1 page of hypercall for now */
+ if (pages != 1)
+ return -ENOMEM;
Why does it matter? If you're only using hypercalls in the first page,
it doesn't matter whether Xen exports more pages beyond that.
+
+ pfn = __pa(hypercall_page);
+ wrmsrl(msr, pfn);
wrmsr_safe() with error check, just in case it fails?
+
+ xen_setup_features();
+
+ x86_init.oem.banner = xen_hvm_pv_banner;
+ pv_info = xen_hvm_pv_info;
+
+ xen_domain_type = XEN_HVM_DOMAIN;
Set this very last, once everything else has successfully set up.
+
+ return 0;
+}
+
+static struct shared_info shared_info_page __page_aligned_bss;
+
+static void __init init_shared_info(void)
+{
+ struct xen_add_to_physmap xatp;
+
+ xatp.domid = DOMID_SELF;
+ xatp.idx = 0;
+ xatp.space = XENMAPSPACE_shared_info;
+ xatp.gpfn = __pa(&shared_info_page)>> PAGE_SHIFT;
+ if (HYPERVISOR_memory_op(XENMEM_add_to_physmap,&xatp))
+ BUG();
It isn't too late to back out if it fails; just return an error code.
+
+ HYPERVISOR_shared_info = (struct shared_info *)&shared_info_page;
+
+ per_cpu(xen_vcpu, 0) =&HYPERVISOR_shared_info->vcpu_info[0];
+}
+
+void __init xen_guest_init(void)
+{
+ int r;
+
+ /* Ensure the we won't confused with others */
+ if (xen_domain_type != XEN_NATIVE)
Just use xen_domain()?
+ return;
+
+ r = init_hvm_pv_info();
+ if (r< 0)
+ return;
+
+ init_shared_info();
+}
diff --git a/include/xen/interface/hvm/hvm_op.h b/include/xen/interface/hvm/hvm_op.h
index 7c74ba4..3f0b118 100644
--- a/include/xen/interface/hvm/hvm_op.h
+++ b/include/xen/interface/hvm/hvm_op.h
@@ -69,4 +69,12 @@ DEFINE_GUEST_HANDLE_STRUCT(xen_hvm_set_pci_link_route);
/* Flushes all VCPU TLBs: @arg must be NULL. */
#define HVMOP_flush_tlbs 5
+#define HVMOP_enable_pv 9
+struct xen_hvm_pv_type {
+ domid_t domid;
+ uint32_t flags;
+#define HVM_PV_CLOCK (1ull<<0)
+#define HVM_PV_EVTCHN (1ull<<1)
+};
+
#endif /* __XEN_PUBLIC_HVM_HVM_OP_H__ */
diff --git a/include/xen/xen.h b/include/xen/xen.h
index a164024..11f5ced 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -19,6 +19,15 @@ extern enum xen_domain_type xen_domain_type;
#define xen_hvm_domain() (xen_domain()&& \
xen_domain_type == XEN_HVM_DOMAIN)
+#ifdef CONFIG_XEN_HVM_PV
+
+#define XEN_HVM_PV_EVTCHN_ENABLED (1u<< 1)
+extern u32 xen_hvm_pv_features;
+
+#define xen_hvm_pv_evtchn_enabled() \
+ (xen_hvm_pv_features& XEN_HVM_PV_EVTCHN_ENABLED)
+#endif /* CONFIG_XEN_HVM_PV */
Did you compile test this with !CONFIG_XEN_HVM_PV? I think it would
fail with xen_hvm_pv_evtchn_enabled() undefined. Fortunately making
xen_hvm_pv_evtchn_enabled() evaluate to constant 0 in the !configed case
will clean things up.
J
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/