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Message-ID: <20120715160653.GA22779@aepfle.de>
Date: Sun, 15 Jul 2012 18:06:53 +0200
From: Olaf Hering <olaf@...fle.de>
To: Keir Fraser <keir.xen@...il.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Jan Beulich <JBeulich@...e.com>, xen-devel@...ts.xensource.com,
kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
Daniel Kiper <dkiper@...-space.pl>
Subject: Re: [Xen-devel] incorrect layout of globals from head_64.S during
kexec boot
On Tue, Jul 10, Keir Fraser wrote:
> Best thing to do, is possible, is map the shared-info page in the
> xen-platform pci device's BAR memory range. Then it will not conflict with
> any RAM.
This patch does that. I did a kexec boot and a save/restore.
It does not deal with the possible race were the old pfn is not backed
by a mfn.
Olaf
commit a9d5567c67a2317c9db174a4deef6c5690220749
Author: Olaf Hering <olaf@...fle.de>
Date: Thu Jul 12 19:38:39 2012 +0200
xen PVonHVM: move shared info page from RAM to MMIO
Signed-off-by: Olaf Hering <ohering@...e.de>
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index ff962d4..8a743af 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1465,23 +1465,22 @@ static int init_hvm_pv_info(int *major, int *minor)
return 0;
}
-void __ref xen_hvm_init_shared_info(void)
+static struct shared_info *hvm_shared_info;
+static unsigned long hvm_shared_info_pfn;
+
+static void __ref set_shared_info(struct shared_info *sip, unsigned long pfn)
{
int cpu;
struct xen_add_to_physmap xatp;
- static struct shared_info *shared_info_page = 0;
- if (!shared_info_page)
- shared_info_page = (struct shared_info *)
- extend_brk(PAGE_SIZE, PAGE_SIZE);
xatp.domid = DOMID_SELF;
xatp.idx = 0;
xatp.space = XENMAPSPACE_shared_info;
- xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT;
+ xatp.gpfn = pfn;
if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
BUG();
- HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;
+ HYPERVISOR_shared_info = sip;
/* xen_vcpu is a pointer to the vcpu_info struct in the shared_info
* page, we use it in the event channel upcall and in some pvclock
@@ -1494,8 +1493,48 @@ void __ref xen_hvm_init_shared_info(void)
for_each_online_cpu(cpu) {
per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
}
+ mb();
}
+/* Reconnect the pfn to a mfn */
+void __ref xen_hvm_resume_shared_info(void)
+{
+ set_shared_info(hvm_shared_info, hvm_shared_info_pfn);
+}
+
+/* Move the pfn in RAM to a pfn in MMIO space */
+void __ref xen_hvm_finalize_shared_info(struct shared_info *sip, unsigned long pfn)
+{
+ struct xen_memory_reservation reservation = {
+ .domid = DOMID_SELF,
+ .nr_extents = 1,
+ };
+ int rc;
+
+ set_xen_guest_handle(reservation.extent_start, &hvm_shared_info_pfn);
+
+ /* Move pfn, disconnects previous pfn from mfn */
+ set_shared_info(sip, pfn);
+
+ /* Allocate new mfn for previous pfn */
+ rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+ WARN_ON(rc != 1);
+
+ /* Remember final pfn and pointer for resume */
+ hvm_shared_info_pfn = pfn;
+ hvm_shared_info = sip;
+}
+
+/* Use a pfn in RAM until PCI init is done. */
+static void __ref xen_hvm_initial_shared_info(void)
+{
+ /* FIXME simply allocate a page and release it after pfn move (How at this stage?) */
+ hvm_shared_info = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ hvm_shared_info_pfn = __pa(hvm_shared_info) >> PAGE_SHIFT;
+ set_shared_info(hvm_shared_info, hvm_shared_info_pfn);
+}
+
+
#ifdef CONFIG_XEN_PVHVM
static int __cpuinit xen_hvm_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
@@ -1526,7 +1565,7 @@ static void __init xen_hvm_guest_init(void)
if (r < 0)
return;
- xen_hvm_init_shared_info();
+ xen_hvm_initial_shared_info();
if (xen_feature(XENFEAT_hvm_callback_vector))
xen_have_vector_callback = 1;
diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index 45329c8..ae8a00c 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -30,7 +30,7 @@ void xen_arch_hvm_post_suspend(int suspend_cancelled)
{
#ifdef CONFIG_XEN_PVHVM
int cpu;
- xen_hvm_init_shared_info();
+ xen_hvm_resume_shared_info();
xen_callback_vector();
xen_unplug_emulated_devices();
if (xen_feature(XENFEAT_hvm_safe_pvclock)) {
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 202d4c1..1e4329e 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -41,7 +41,7 @@ void xen_enable_syscall(void);
void xen_vcpu_restore(void);
void xen_callback_vector(void);
-void xen_hvm_init_shared_info(void);
+void xen_hvm_resume_shared_info(void);
void xen_unplug_emulated_devices(void);
void __init xen_build_dynamic_phys_to_machine(void);
diff --git a/drivers/xen/platform-pci.c b/drivers/xen/platform-pci.c
index 97ca359..cbe866b 100644
--- a/drivers/xen/platform-pci.c
+++ b/drivers/xen/platform-pci.c
@@ -108,6 +108,8 @@ static int __devinit platform_pci_init(struct pci_dev *pdev,
long ioaddr;
long mmio_addr, mmio_len;
unsigned int max_nr_gframes;
+ unsigned long addr;
+ struct shared_info *hvm_shared_info;
if (!xen_domain())
return -ENODEV;
@@ -138,6 +140,11 @@ static int __devinit platform_pci_init(struct pci_dev *pdev,
platform_mmio = mmio_addr;
platform_mmiolen = mmio_len;
+ addr = alloc_xen_mmio(PAGE_SIZE);
+ hvm_shared_info = ioremap(addr, PAGE_SIZE);
+ memset(hvm_shared_info, 0, PAGE_SIZE);
+ xen_hvm_finalize_shared_info(hvm_shared_info, addr >> PAGE_SHIFT);
+
if (!xen_have_vector_callback) {
ret = xen_allocate_irq(pdev);
if (ret) {
diff --git a/include/xen/events.h b/include/xen/events.h
index 04399b2..3337698 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -58,6 +58,8 @@ void notify_remote_via_irq(int irq);
void xen_irq_resume(void);
+void xen_hvm_finalize_shared_info(struct shared_info *sip, unsigned long pfn);
+
/* Clear an irq's pending state, in preparation for polling on it */
void xen_clear_irq_pending(int irq);
void xen_set_irq_pending(int irq);
--
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