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authorLinus Torvalds <torvalds@linux-foundation.org>2012-08-25 17:31:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-08-25 17:31:59 -0700
commit267560874cb0189f28e7ae6dfbc8e98b8848be98 (patch)
tree649702ebe9faf5679d6e81c08dc07c4fcb04a2dd /arch
parent4ae4614712e0a354c9e6c286c0db1612246766ce (diff)
parentc96aae1f7f393387d160211f60398d58463a7e65 (diff)
downloadlinux-linaro-stable-267560874cb0189f28e7ae6dfbc8e98b8848be98.tar.gz
Merge tag 'stable/for-linus-3.6-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen
Pull three xen bug-fixes from Konrad Rzeszutek Wilk: - Revert the kexec fix which caused on non-kexec shutdowns a race. - Reuse existing P2M leafs - instead of requiring to allocate a large area of bootup virtual address estate. - Fix a one-off error when adding PFNs for balloon pages. * tag 'stable/for-linus-3.6-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: xen/setup: Fix one-off error when adding for-balloon PFNs to the P2M. xen/p2m: Reuse existing P2M leafs if they are filled with 1:1 PFNs or INVALID. Revert "xen PVonHVM: move shared_info to MMIO before kexec"
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/xen/enlighten.c118
-rw-r--r--arch/x86/xen/p2m.c95
-rw-r--r--arch/x86/xen/setup.c9
-rw-r--r--arch/x86/xen/suspend.c2
-rw-r--r--arch/x86/xen/xen-ops.h2
5 files changed, 113 insertions, 113 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index bf4bda6d3e9a..9642d4a38602 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -31,7 +31,6 @@
#include <linux/pci.h>
#include <linux/gfp.h>
#include <linux/memblock.h>
-#include <linux/syscore_ops.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
@@ -1470,130 +1469,38 @@ asmlinkage void __init xen_start_kernel(void)
#endif
}
-#ifdef CONFIG_XEN_PVHVM
-/*
- * The pfn containing the shared_info is located somewhere in RAM. This
- * will cause trouble if the current kernel is doing a kexec boot into a
- * new kernel. The new kernel (and its startup code) can not know where
- * the pfn is, so it can not reserve the page. The hypervisor will
- * continue to update the pfn, and as a result memory corruption occours
- * in the new kernel.
- *
- * One way to work around this issue is to allocate a page in the
- * xen-platform pci device's BAR memory range. But pci init is done very
- * late and the shared_info page is already in use very early to read
- * the pvclock. So moving the pfn from RAM to MMIO is racy because some
- * code paths on other vcpus could access the pfn during the small
- * window when the old pfn is moved to the new pfn. There is even a
- * small window were the old pfn is not backed by a mfn, and during that
- * time all reads return -1.
- *
- * Because it is not known upfront where the MMIO region is located it
- * can not be used right from the start in xen_hvm_init_shared_info.
- *
- * To minimise trouble the move of the pfn is done shortly before kexec.
- * This does not eliminate the race because all vcpus are still online
- * when the syscore_ops will be called. But hopefully there is no work
- * pending at this point in time. Also the syscore_op is run last which
- * reduces the risk further.
- */
-
-static struct shared_info *xen_hvm_shared_info;
-
-static void xen_hvm_connect_shared_info(unsigned long pfn)
+void __ref xen_hvm_init_shared_info(void)
{
+ 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 = pfn;
+ xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT;
if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
BUG();
-}
-static void xen_hvm_set_shared_info(struct shared_info *sip)
-{
- int cpu;
-
- HYPERVISOR_shared_info = sip;
+ HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;
/* 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
* related functions. We don't need the vcpu_info placement
* optimizations because we don't use any pv_mmu or pv_irq op on
* HVM.
- * When xen_hvm_set_shared_info is run at boot time only vcpu 0 is
- * online but xen_hvm_set_shared_info is run at resume time too and
+ * When xen_hvm_init_shared_info is run at boot time only vcpu 0 is
+ * online but xen_hvm_init_shared_info is run at resume time too and
* in that case multiple vcpus might be online. */
for_each_online_cpu(cpu) {
per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
}
}
-/* Reconnect the shared_info pfn to a mfn */
-void xen_hvm_resume_shared_info(void)
-{
- xen_hvm_connect_shared_info(__pa(xen_hvm_shared_info) >> PAGE_SHIFT);
-}
-
-#ifdef CONFIG_KEXEC
-static struct shared_info *xen_hvm_shared_info_kexec;
-static unsigned long xen_hvm_shared_info_pfn_kexec;
-
-/* Remember a pfn in MMIO space for kexec reboot */
-void __devinit xen_hvm_prepare_kexec(struct shared_info *sip, unsigned long pfn)
-{
- xen_hvm_shared_info_kexec = sip;
- xen_hvm_shared_info_pfn_kexec = pfn;
-}
-
-static void xen_hvm_syscore_shutdown(void)
-{
- struct xen_memory_reservation reservation = {
- .domid = DOMID_SELF,
- .nr_extents = 1,
- };
- unsigned long prev_pfn;
- int rc;
-
- if (!xen_hvm_shared_info_kexec)
- return;
-
- prev_pfn = __pa(xen_hvm_shared_info) >> PAGE_SHIFT;
- set_xen_guest_handle(reservation.extent_start, &prev_pfn);
-
- /* Move pfn to MMIO, disconnects previous pfn from mfn */
- xen_hvm_connect_shared_info(xen_hvm_shared_info_pfn_kexec);
-
- /* Update pointers, following hypercall is also a memory barrier */
- xen_hvm_set_shared_info(xen_hvm_shared_info_kexec);
-
- /* Allocate new mfn for previous pfn */
- do {
- rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
- if (rc == 0)
- msleep(123);
- } while (rc == 0);
-
- /* Make sure the previous pfn is really connected to a (new) mfn */
- BUG_ON(rc != 1);
-}
-
-static struct syscore_ops xen_hvm_syscore_ops = {
- .shutdown = xen_hvm_syscore_shutdown,
-};
-#endif
-
-/* Use a pfn in RAM, may move to MMIO before kexec. */
-static void __init xen_hvm_init_shared_info(void)
-{
- /* Remember pointer for resume */
- xen_hvm_shared_info = extend_brk(PAGE_SIZE, PAGE_SIZE);
- xen_hvm_connect_shared_info(__pa(xen_hvm_shared_info) >> PAGE_SHIFT);
- xen_hvm_set_shared_info(xen_hvm_shared_info);
-}
-
+#ifdef CONFIG_XEN_PVHVM
static void __init init_hvm_pv_info(void)
{
int major, minor;
@@ -1644,9 +1551,6 @@ static void __init xen_hvm_guest_init(void)
init_hvm_pv_info();
xen_hvm_init_shared_info();
-#ifdef CONFIG_KEXEC
- register_syscore_ops(&xen_hvm_syscore_ops);
-#endif
if (xen_feature(XENFEAT_hvm_callback_vector))
xen_have_vector_callback = 1;
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index b2e91d40a4cb..d4b255463253 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -196,9 +196,11 @@ RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3);
/* When we populate back during bootup, the amount of pages can vary. The
* max we have is seen is 395979, but that does not mean it can't be more.
- * But some machines can have 3GB I/O holes even. So lets reserve enough
- * for 4GB of I/O and E820 holes. */
-RESERVE_BRK(p2m_populated, PMD_SIZE * 4);
+ * Some machines can have 3GB I/O holes even. With early_can_reuse_p2m_middle
+ * it can re-use Xen provided mfn_list array, so we only need to allocate at
+ * most three P2M top nodes. */
+RESERVE_BRK(p2m_populated, PAGE_SIZE * 3);
+
static inline unsigned p2m_top_index(unsigned long pfn)
{
BUG_ON(pfn >= MAX_P2M_PFN);
@@ -575,12 +577,99 @@ static bool __init early_alloc_p2m(unsigned long pfn)
}
return true;
}
+
+/*
+ * Skim over the P2M tree looking at pages that are either filled with
+ * INVALID_P2M_ENTRY or with 1:1 PFNs. If found, re-use that page and
+ * replace the P2M leaf with a p2m_missing or p2m_identity.
+ * Stick the old page in the new P2M tree location.
+ */
+bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_mfn)
+{
+ unsigned topidx;
+ unsigned mididx;
+ unsigned ident_pfns;
+ unsigned inv_pfns;
+ unsigned long *p2m;
+ unsigned long *mid_mfn_p;
+ unsigned idx;
+ unsigned long pfn;
+
+ /* We only look when this entails a P2M middle layer */
+ if (p2m_index(set_pfn))
+ return false;
+
+ for (pfn = 0; pfn <= MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) {
+ topidx = p2m_top_index(pfn);
+
+ if (!p2m_top[topidx])
+ continue;
+
+ if (p2m_top[topidx] == p2m_mid_missing)
+ continue;
+
+ mididx = p2m_mid_index(pfn);
+ p2m = p2m_top[topidx][mididx];
+ if (!p2m)
+ continue;
+
+ if ((p2m == p2m_missing) || (p2m == p2m_identity))
+ continue;
+
+ if ((unsigned long)p2m == INVALID_P2M_ENTRY)
+ continue;
+
+ ident_pfns = 0;
+ inv_pfns = 0;
+ for (idx = 0; idx < P2M_PER_PAGE; idx++) {
+ /* IDENTITY_PFNs are 1:1 */
+ if (p2m[idx] == IDENTITY_FRAME(pfn + idx))
+ ident_pfns++;
+ else if (p2m[idx] == INVALID_P2M_ENTRY)
+ inv_pfns++;
+ else
+ break;
+ }
+ if ((ident_pfns == P2M_PER_PAGE) || (inv_pfns == P2M_PER_PAGE))
+ goto found;
+ }
+ return false;
+found:
+ /* Found one, replace old with p2m_identity or p2m_missing */
+ p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing);
+ /* And the other for save/restore.. */
+ mid_mfn_p = p2m_top_mfn_p[topidx];
+ /* NOTE: Even if it is a p2m_identity it should still be point to
+ * a page filled with INVALID_P2M_ENTRY entries. */
+ mid_mfn_p[mididx] = virt_to_mfn(p2m_missing);
+
+ /* Reset where we want to stick the old page in. */
+ topidx = p2m_top_index(set_pfn);
+ mididx = p2m_mid_index(set_pfn);
+
+ /* This shouldn't happen */
+ if (WARN_ON(p2m_top[topidx] == p2m_mid_missing))
+ early_alloc_p2m(set_pfn);
+
+ if (WARN_ON(p2m_top[topidx][mididx] != p2m_missing))
+ return false;
+
+ p2m_init(p2m);
+ p2m_top[topidx][mididx] = p2m;
+ mid_mfn_p = p2m_top_mfn_p[topidx];
+ mid_mfn_p[mididx] = virt_to_mfn(p2m);
+
+ return true;
+}
bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn)
{
if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
if (!early_alloc_p2m(pfn))
return false;
+ if (early_can_reuse_p2m_middle(pfn, mfn))
+ return __set_phys_to_machine(pfn, mfn);
+
if (!early_alloc_p2m_middle(pfn, false /* boundary crossover OK!*/))
return false;
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index ead85576d54a..d11ca11d14fc 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -78,9 +78,16 @@ static void __init xen_add_extra_mem(u64 start, u64 size)
memblock_reserve(start, size);
xen_max_p2m_pfn = PFN_DOWN(start + size);
+ for (pfn = PFN_DOWN(start); pfn < xen_max_p2m_pfn; pfn++) {
+ unsigned long mfn = pfn_to_mfn(pfn);
+
+ if (WARN(mfn == pfn, "Trying to over-write 1-1 mapping (pfn: %lx)\n", pfn))
+ continue;
+ WARN(mfn != INVALID_P2M_ENTRY, "Trying to remove %lx which has %lx mfn!\n",
+ pfn, mfn);
- for (pfn = PFN_DOWN(start); pfn <= xen_max_p2m_pfn; pfn++)
__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+ }
}
static unsigned long __init xen_do_chunk(unsigned long start,
diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index ae8a00c39de4..45329c8c226e 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_resume_shared_info();
+ xen_hvm_init_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 1e4329e04e0f..202d4c150154 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_resume_shared_info(void);
+void xen_hvm_init_shared_info(void);
void xen_unplug_emulated_devices(void);
void __init xen_build_dynamic_phys_to_machine(void);