Revert "xen PVonHVM: move shared_info to MMIO before kexec" (ca08649e) · Commits · 戴 / test

arch/x86/xen/enlighten.c

+11 −107

Original line number	Diff line number	Diff line
		@@ -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>
		@@ -1472,130 +1471,38 @@ 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;
		@@ -1646,9 +1553,6 @@ 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;

arch/x86/xen/suspend.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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)) {

arch/x86/xen/xen-ops.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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);

drivers/xen/platform-pci.c

+0 −15

Original line number	Diff line number	Diff line
		@@ -101,19 +101,6 @@ static int platform_pci_resume(struct pci_dev *pdev)
		return 0;
		}

		static void __devinit prepare_shared_info(void)
		{
		#ifdef CONFIG_KEXEC
		unsigned long addr;
		struct shared_info *hvm_shared_info;

		addr = alloc_xen_mmio(PAGE_SIZE);
		hvm_shared_info = ioremap(addr, PAGE_SIZE);
		memset(hvm_shared_info, 0, PAGE_SIZE);
		xen_hvm_prepare_kexec(hvm_shared_info, addr >> PAGE_SHIFT);
		#endif
		}

		static int __devinit platform_pci_init(struct pci_dev *pdev,
		const struct pci_device_id *ent)
		{
		@@ -151,8 +138,6 @@ static int __devinit platform_pci_init(struct pci_dev *pdev,
		platform_mmio = mmio_addr;
		platform_mmiolen = mmio_len;

		prepare_shared_info();

		if (!xen_have_vector_callback) {
		ret = xen_allocate_irq(pdev);
		if (ret) {

include/xen/events.h

+0 −2

Original line number	Diff line number	Diff line
		@@ -58,8 +58,6 @@ void notify_remote_via_irq(int irq);

		void xen_irq_resume(void);

		void xen_hvm_prepare_kexec(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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