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2a31b9db15
There are two problems with KVM_GET_DIRTY_LOG. First, and less important,
it can take kvm->mmu_lock for an extended period of time. Second, its user
can actually see many false positives in some cases. The latter is due
to a benign race like this:
1. KVM_GET_DIRTY_LOG returns a set of dirty pages and write protects
them.
2. The guest modifies the pages, causing them to be marked ditry.
3. Userspace actually copies the pages.
4. KVM_GET_DIRTY_LOG returns those pages as dirty again, even though
they were not written to since (3).
This is especially a problem for large guests, where the time between
(1) and (3) can be substantial. This patch introduces a new
capability which, when enabled, makes KVM_GET_DIRTY_LOG not
write-protect the pages it returns. Instead, userspace has to
explicitly clear the dirty log bits just before using the content
of the page. The new KVM_CLEAR_DIRTY_LOG ioctl can also operate on a
64-page granularity rather than requiring to sync a full memslot;
this way, the mmu_lock is taken for small amounts of time, and
only a small amount of time will pass between write protection
of pages and the sending of their content.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
59 lines
1.9 KiB
Makefile
59 lines
1.9 KiB
Makefile
all:
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top_srcdir = ../../../..
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KSFT_KHDR_INSTALL := 1
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UNAME_M := $(shell uname -m)
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LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/ucall.c lib/sparsebit.c
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LIBKVM_x86_64 = lib/x86_64/processor.c lib/x86_64/vmx.c
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LIBKVM_aarch64 = lib/aarch64/processor.c
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TEST_GEN_PROGS_x86_64 = x86_64/platform_info_test
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TEST_GEN_PROGS_x86_64 += x86_64/set_sregs_test
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TEST_GEN_PROGS_x86_64 += x86_64/sync_regs_test
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TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test
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TEST_GEN_PROGS_x86_64 += x86_64/cr4_cpuid_sync_test
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TEST_GEN_PROGS_x86_64 += x86_64/state_test
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TEST_GEN_PROGS_x86_64 += x86_64/evmcs_test
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TEST_GEN_PROGS_x86_64 += dirty_log_test
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TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
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TEST_GEN_PROGS_aarch64 += dirty_log_test
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TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
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TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
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LIBKVM += $(LIBKVM_$(UNAME_M))
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INSTALL_HDR_PATH = $(top_srcdir)/usr
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LINUX_HDR_PATH = $(INSTALL_HDR_PATH)/include/
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LINUX_TOOL_INCLUDE = $(top_srcdir)/tools/include
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CFLAGS += -O2 -g -std=gnu99 -I$(LINUX_TOOL_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude -I$(<D) -Iinclude/$(UNAME_M) -I..
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LDFLAGS += -pthread
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# After inclusion, $(OUTPUT) is defined and
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# $(TEST_GEN_PROGS) starts with $(OUTPUT)/
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include ../lib.mk
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STATIC_LIBS := $(OUTPUT)/libkvm.a
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LIBKVM_OBJ := $(patsubst %.c, $(OUTPUT)/%.o, $(LIBKVM))
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EXTRA_CLEAN += $(LIBKVM_OBJ) $(STATIC_LIBS) cscope.*
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x := $(shell mkdir -p $(sort $(dir $(LIBKVM_OBJ))))
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$(LIBKVM_OBJ): $(OUTPUT)/%.o: %.c
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$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $@
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$(OUTPUT)/libkvm.a: $(LIBKVM_OBJ)
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$(AR) crs $@ $^
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all: $(STATIC_LIBS)
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$(TEST_GEN_PROGS): $(STATIC_LIBS)
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cscope: include_paths = $(LINUX_TOOL_INCLUDE) $(LINUX_HDR_PATH) include lib ..
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cscope:
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$(RM) cscope.*
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(find $(include_paths) -name '*.h' \
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-exec realpath --relative-base=$(PWD) {} \;; \
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find . -name '*.c' \
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-exec realpath --relative-base=$(PWD) {} \;) | sort -u > cscope.files
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cscope -b
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