[1/3] KVM: Support for guest page hinting

Commit Message

Nitesh Lal Aug. 1, 2017, 8:48 p.m. UTC

This patch includes the following:
1. Basic skeleton for the support
2. Enablement of x86 platform to use the same

Signed-off-by: Nitesh Narayan Lal <[e-mail]>
---
 arch/x86/kvm/Makefile   |  1 +
 include/linux/gfp.h     |  7 +++++++
 virt/kvm/Kconfig        |  4 ++++
 virt/kvm/page_hinting.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 58 insertions(+)
 create mode 100644 virt/kvm/page_hinting.c

Comments

kernel test robot Aug. 2, 2017, 7:12 a.m. UTC | #1

Hi Nitesh,

[auto build test ERROR on kvm/linux-next]
[also build test ERROR on v4.13-rc3 next-20170801]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Nitesh-Narayan-Lal/KVM-Guest-page-hinting/20170802-130559
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
config: x86_64-rhel (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   mm/page_alloc.o: In function `__free_pages_ok':
>> page_alloc.c:(.text+0x16e9): undefined reference to `arch_free_page'
   mm/page_alloc.o: In function `post_alloc_hook':
>> page_alloc.c:(.text+0x2424): undefined reference to `arch_alloc_page'
   mm/page_alloc.o: In function `free_hot_cold_page':
   page_alloc.c:(.text+0x3307): undefined reference to `arch_free_page'
   mm/page_alloc.o: In function `get_page_from_freelist':
   page_alloc.c:(.text+0x3fdd): undefined reference to `arch_alloc_page'
   page_alloc.c:(.text+0x45e3): undefined reference to `arch_alloc_page'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Patch

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 09d4b17..6f7c382 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -10,6 +10,7 @@  KVM := ../../../virt/kvm
 kvm-y			+= $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o \
 				$(KVM)/eventfd.o $(KVM)/irqchip.o $(KVM)/vfio.o
 kvm-$(CONFIG_KVM_ASYNC_PF)	+= $(KVM)/async_pf.o
+kvm-$(CONFIG_KVM_FREE_PAGE_HINTING)	+= $(KVM)/page_hinting.o
 
 kvm-y			+= x86.o mmu.o emulate.o i8259.o irq.o lapic.o \
 			   i8254.o ioapic.o irq_comm.o cpuid.o pmu.o mtrr.o \
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index a89d37e..37963b8 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -424,6 +424,13 @@  static inline struct zonelist *node_zonelist(int nid, gfp_t flags)
 	return NODE_DATA(nid)->node_zonelists + gfp_zonelist(flags);
 }
 
+#ifdef	CONFIG_KVM_FREE_PAGE_HINTING
+#define HAVE_ARCH_ALLOC_PAGE
+#define HAVE_ARCH_FREE_PAGE
+void arch_free_page(struct page *page, int order);
+void arch_alloc_page(struct page *page, int order);
+#endif
+
 #ifndef HAVE_ARCH_FREE_PAGE
 static inline void arch_free_page(struct page *page, int order) { }
 #endif
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index b0cc1a3..57f1c7b 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -50,3 +50,7 @@  config KVM_COMPAT
 
 config HAVE_KVM_IRQ_BYPASS
        bool
+
+config KVM_FREE_PAGE_HINTING
+       def_bool m
+       depends on KVM
diff --git a/virt/kvm/page_hinting.c b/virt/kvm/page_hinting.c
new file mode 100644
index 0000000..39d2b1d
--- /dev/null
+++ b/virt/kvm/page_hinting.c
@@ -0,0 +1,46 @@ 
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/page_ref.h>
+#include <linux/kvm_host.h>
+#include <linux/sort.h>
+
+#include <trace/events/kvm.h>
+
+#define MAX_FGPT_ENTRIES	1000
+#define HYPERLIST_THRESHOLD	500
+/*
+ * struct kvm_free_pages - Tracks the pages which are freed by the guest.
+ * @pfn	- page frame number for the page which is to be freed
+ * @pages - number of pages which are supposed to be freed.
+ * A global array object is used to hold the list of pfn and number of pages
+ * which are freed by the guest. This list may also have fragmentated pages so
+ * defragmentation is a must prior to the hypercall.
+ */
+struct kvm_free_pages {
+	unsigned long pfn;
+	unsigned int pages;
+};
+
+/*
+ * hypervisor_pages - It is a dummy structure passed with the hypercall.
+ * @pfn - page frame number for the page which is to be freed.
+ * @pages - number of pages which are supposed to be freed.
+ * A global array object is used to to hold the list of pfn and pages and is
+ * passed as part of the hypercall.
+ */
+struct hypervisor_pages {
+	unsigned long pfn;
+	unsigned int pages;
+};
+
+DEFINE_PER_CPU(struct kvm_free_pages [MAX_FGPT_ENTRIES], kvm_pt);
+DEFINE_PER_CPU(int, kvm_pt_idx);
+struct hypervisor_pages hypervisor_pagelist[MAX_FGPT_ENTRIES];
+
+void arch_alloc_page(struct page *page, int order)
+{
+}
+
+void arch_free_page(struct page *page, int order)
+{
+}