| Message ID | 4dcaa893.5925e30a.0f9e.125c@mx.google.com (mailing list archive) |
|---|---|
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* levinsasha928@gmail.com <levinsasha928@gmail.com> wrote: > @@ -225,7 +266,18 @@ struct kvm *kvm__init(const char *kvm_dev, unsigned long ram_size) > > self->ram_size = ram_size; > > - self->ram_start = mmap(NULL, ram_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); > + if (self->ram_size < KVM_32BIT_GAP_START) { > + self->ram_start = mmap(NULL, ram_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); > + } else { > + self->ram_start = mmap(NULL, ram_size + KVM_32BIT_GAP_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); > + if (self->ram_start != MAP_FAILED) { > + /* > + * We mprotect the gap (see kvm__init_ram() for details) PROT_NONE so that > + * if we accidently write to it, we will know. > + */ > + mprotect(self->ram_start + KVM_32BIT_GAP_START, KVM_32BIT_GAP_SIZE, PROT_NONE); Nit: the mmaps here wrap off the end of line. It would be a lot more easier to read if kvm.h defined two helpers, like: #define PROT_RW (PROT_READ|PROT_WRITE) #define MAP_ANON (MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE) So the mmaps() would become a bit more readable: > + if (self->ram_size < KVM_32BIT_GAP_START) { > + self->ram_start = mmap(NULL, ram_size, PROT_RW, MAP_ANON, -1, 0); > + } else { > + self->ram_start = mmap(NULL, ram_size + KVM_32BIT_GAP_SIZE, PROT_RW, MAP_ANON, -1, 0); > + if (self->ram_start != MAP_FAILED) { > + /* > + * We mprotect the gap (see kvm__init_ram() for details) PROT_NONE so that > + * if we accidently write to it, we will know. > + */ > + mprotect(self->ram_start + KVM_32BIT_GAP_START, KVM_32BIT_GAP_SIZE, PROT_NONE); I'll test your series. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 11 May 2011, Ingo Molnar wrote: > Ok, with your fixes applied i can boot a 10 GB RAM guest just fine - both the > hang and the later IO errors and IO corruptions are gone: > > [root@aldebaran ~]# free > total used free shared buffers cached > Mem: 10019972 150436 9869536 0 79136 17296 > -/+ buffers/cache: 54004 9965968 > Swap: 4096568 0 4096568 > > Acked-and-tested-by: Ingo Molnar <mingo@elte.hu> Excellent! Thanks guys! Pekka -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05/11/2011 11:17 PM, levinsasha928@gmail.com wrote: > From: Sasha Levin <levinsasha928@gmail.com> > > e820 is expected to leave a memory gap within the low 32 > bits of RAM space. From the documentation of e820_setup_gap(): > /* > * Search for the biggest gap in the low 32 bits of the e820 > * memory space. We pass this space to PCI to assign MMIO resources > * for hotplug or unconfigured devices in. > * Hopefully the BIOS let enough space left. > */ > > Not leaving such gap causes errors and hangs during the boot > process. > > This patch adds a memory gap between 0xe0000000 and 0x100000000 > when using more than 0xe0000000 bytes for guest RAM. > > This patch updates the e820 table, slot allocations > used for KVM_SET_USER_MEMORY_REGION. > > Changes in V2: > - Allocate RAM with the gap to avoid altering the translation code. > - New patch description. > > Changes in V3: > - Remove unnecessary casts. > > Changes in V4: > - Rewrite kvm__init_ram(). > - Document the 64bit gap within the code. > > Signed-off-by: Sasha Levin <levinsasha928@gmail.com> > --- > tools/kvm/bios.c | 27 ++++++++++++---- > tools/kvm/include/kvm/e820.h | 2 +- > tools/kvm/include/kvm/kvm.h | 2 + > tools/kvm/kvm.c | 66 +++++++++++++++++++++++++++++++++++++---- > 4 files changed, 82 insertions(+), 15 deletions(-) > > diff --git a/tools/kvm/bios.c b/tools/kvm/bios.c > index 2199c0c..3cd9b24 100644 > --- a/tools/kvm/bios.c > +++ b/tools/kvm/bios.c > @@ -61,8 +61,6 @@ static void e820_setup(struct kvm *kvm) > size = guest_flat_to_host(kvm, E820_MAP_SIZE); > mem_map = guest_flat_to_host(kvm, E820_MAP_START); > > - *size = E820_MEM_AREAS; > - > mem_map[i++] = (struct e820_entry) { > .addr = REAL_MODE_IVT_BEGIN, > .size = EBDA_START - REAL_MODE_IVT_BEGIN, > @@ -78,13 +76,28 @@ static void e820_setup(struct kvm *kvm) > .size = MB_BIOS_END - MB_BIOS_BEGIN, > .type = E820_MEM_RESERVED, > }; > - mem_map[i++] = (struct e820_entry) { > - .addr = BZ_KERNEL_START, > - .size = kvm->ram_size - BZ_KERNEL_START, > - .type = E820_MEM_USABLE, > - }; > + if (kvm->ram_size < KVM_32BIT_GAP_START) { > + mem_map[i++] = (struct e820_entry) { > + .addr = BZ_KERNEL_START, > + .size = kvm->ram_size - BZ_KERNEL_START, > + .type = E820_MEM_USABLE, > + }; > + } else { > + mem_map[i++] = (struct e820_entry) { > + .addr = BZ_KERNEL_START, > + .size = KVM_32BIT_GAP_START - BZ_KERNEL_START, > + .type = E820_MEM_USABLE, > + }; > + mem_map[i++] = (struct e820_entry) { > + .addr = 0x100000000ULL, > + .size = kvm->ram_size - KVM_32BIT_GAP_START, > + .type = E820_MEM_USABLE, > + }; > + } > > BUILD_BUG_ON(i > E820_MEM_AREAS); > + > + *size = i; > } > > /** > diff --git a/tools/kvm/include/kvm/e820.h b/tools/kvm/include/kvm/e820.h > index 252ae1f..e0f5f2a 100644 > --- a/tools/kvm/include/kvm/e820.h > +++ b/tools/kvm/include/kvm/e820.h > @@ -8,7 +8,7 @@ > #define E820_MEM_USABLE 1 > #define E820_MEM_RESERVED 2 > > -#define E820_MEM_AREAS 4 > +#define E820_MEM_AREAS 5 > > struct e820_entry { > u64 addr; /* start of memory segment */ > diff --git a/tools/kvm/include/kvm/kvm.h b/tools/kvm/include/kvm/kvm.h > index 3dab78d..5e2e64c 100644 > --- a/tools/kvm/include/kvm/kvm.h > +++ b/tools/kvm/include/kvm/kvm.h > @@ -8,6 +8,8 @@ > #include <time.h> > > #define KVM_NR_CPUS (255) > +#define KVM_32BIT_GAP_SIZE (512 << 20) > +#define KVM_32BIT_GAP_START ((1ULL << 32) - KVM_32BIT_GAP_SIZE) > > struct kvm { > int sys_fd; /* For system ioctls(), i.e. /dev/kvm */ > diff --git a/tools/kvm/kvm.c b/tools/kvm/kvm.c > index 65793f2..a3d3dd8 100644 > --- a/tools/kvm/kvm.c > +++ b/tools/kvm/kvm.c > @@ -153,23 +153,64 @@ static bool kvm__cpu_supports_vm(void) > return regs.ecx & (1 << feature); > } > > -void kvm__init_ram(struct kvm *self) > +static void kvm_register_mem_slot(struct kvm *kvm, u32 slot, u64 guest_phys, u64 size, void *userspace_addr) > { > struct kvm_userspace_memory_region mem; > int ret; > > mem = (struct kvm_userspace_memory_region) { > - .slot = 0, > - .guest_phys_addr = 0x0UL, > - .memory_size = self->ram_size, > - .userspace_addr = (unsigned long) self->ram_start, > + .slot = slot, > + .guest_phys_addr = guest_phys, > + .memory_size = size, > + .userspace_addr = (u64)userspace_addr, I am seeing: CC kvm.o kvm.c: In function ‘kvm_register_mem_slot’: kvm.c:165:22: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast] cc1: all warnings being treated as errors make: *** [kvm.o] Error 1 with this patch on 32-bit box. > }; > > - ret = ioctl(self->vm_fd, KVM_SET_USER_MEMORY_REGION, &mem); > + ret = ioctl(kvm->vm_fd, KVM_SET_USER_MEMORY_REGION, &mem); > if (ret < 0) > die_perror("KVM_SET_USER_MEMORY_REGION ioctl"); > } > > +/* > + * Allocating RAM size bigger than 4GB requires us to leave a gap > + * in the RAM which is used for PCI MMIO, hotplug, and unconfigured > + * devices (see documentation of e820_setup_gap() for details). > + * > + * If we're required to initialize RAM bigger than 4GB, we will create > + * a gap between 0xe0000000 and 0x100000000 in the guest virtual mem space. > + */ > + > +void kvm__init_ram(struct kvm *self) > +{ > + u64 phys_start, phys_size; > + void *host_mem; > + > + if (self->ram_size < KVM_32BIT_GAP_START) { > + /* Use a single block of RAM for 32bit RAM */ > + > + phys_start = 0; > + phys_size = self->ram_size; > + host_mem = self->ram_start; > + > + kvm_register_mem_slot(self, 0, 0, self->ram_size, self->ram_start); > + } else { > + /* First RAM range from zero to the PCI gap: */ > + > + phys_start = 0; > + phys_size = KVM_32BIT_GAP_START; > + host_mem = self->ram_start; > + > + kvm_register_mem_slot(self, 0, phys_start, phys_size, host_mem); > + > + /* Second RAM range from 4GB to the end of RAM: */ > + > + phys_start = 0x100000000ULL; > + phys_size = self->ram_size - phys_size; > + host_mem = self->ram_start + phys_start; > + > + kvm_register_mem_slot(self, 1, phys_start, phys_size, host_mem); > + } > +} > + > int kvm__max_cpus(struct kvm *self) > { > int ret; > @@ -225,7 +266,18 @@ struct kvm *kvm__init(const char *kvm_dev, unsigned long ram_size) > > self->ram_size = ram_size; > > - self->ram_start = mmap(NULL, ram_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); > + if (self->ram_size < KVM_32BIT_GAP_START) { > + self->ram_start = mmap(NULL, ram_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); > + } else { > + self->ram_start = mmap(NULL, ram_size + KVM_32BIT_GAP_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); > + if (self->ram_start != MAP_FAILED) { > + /* > + * We mprotect the gap (see kvm__init_ram() for details) PROT_NONE so that > + * if we accidently write to it, we will know. > + */ > + mprotect(self->ram_start + KVM_32BIT_GAP_START, KVM_32BIT_GAP_SIZE, PROT_NONE); > + } > + } > if (self->ram_start == MAP_FAILED) > die("out of memory"); >
* Asias He <asias.hejun@gmail.com> wrote: > On 05/11/2011 11:17 PM, levinsasha928@gmail.com wrote: > > From: Sasha Levin <levinsasha928@gmail.com> > > > > e820 is expected to leave a memory gap within the low 32 > > bits of RAM space. From the documentation of e820_setup_gap(): > > /* > > * Search for the biggest gap in the low 32 bits of the e820 > > * memory space. We pass this space to PCI to assign MMIO resources > > * for hotplug or unconfigured devices in. > > * Hopefully the BIOS let enough space left. > > */ > > > > Not leaving such gap causes errors and hangs during the boot > > process. > > > > This patch adds a memory gap between 0xe0000000 and 0x100000000 > > when using more than 0xe0000000 bytes for guest RAM. > > > > This patch updates the e820 table, slot allocations > > used for KVM_SET_USER_MEMORY_REGION. > > > > Changes in V2: > > - Allocate RAM with the gap to avoid altering the translation code. > > - New patch description. > > > > Changes in V3: > > - Remove unnecessary casts. > > > > Changes in V4: > > - Rewrite kvm__init_ram(). > > - Document the 64bit gap within the code. > > > > Signed-off-by: Sasha Levin <levinsasha928@gmail.com> > > --- > > tools/kvm/bios.c | 27 ++++++++++++---- > > tools/kvm/include/kvm/e820.h | 2 +- > > tools/kvm/include/kvm/kvm.h | 2 + > > tools/kvm/kvm.c | 66 +++++++++++++++++++++++++++++++++++++---- > > 4 files changed, 82 insertions(+), 15 deletions(-) > > > > diff --git a/tools/kvm/bios.c b/tools/kvm/bios.c > > index 2199c0c..3cd9b24 100644 > > --- a/tools/kvm/bios.c > > +++ b/tools/kvm/bios.c > > @@ -61,8 +61,6 @@ static void e820_setup(struct kvm *kvm) > > size = guest_flat_to_host(kvm, E820_MAP_SIZE); > > mem_map = guest_flat_to_host(kvm, E820_MAP_START); > > > > - *size = E820_MEM_AREAS; > > - > > mem_map[i++] = (struct e820_entry) { > > .addr = REAL_MODE_IVT_BEGIN, > > .size = EBDA_START - REAL_MODE_IVT_BEGIN, > > @@ -78,13 +76,28 @@ static void e820_setup(struct kvm *kvm) > > .size = MB_BIOS_END - MB_BIOS_BEGIN, > > .type = E820_MEM_RESERVED, > > }; > > - mem_map[i++] = (struct e820_entry) { > > - .addr = BZ_KERNEL_START, > > - .size = kvm->ram_size - BZ_KERNEL_START, > > - .type = E820_MEM_USABLE, > > - }; > > + if (kvm->ram_size < KVM_32BIT_GAP_START) { > > + mem_map[i++] = (struct e820_entry) { > > + .addr = BZ_KERNEL_START, > > + .size = kvm->ram_size - BZ_KERNEL_START, > > + .type = E820_MEM_USABLE, > > + }; > > + } else { > > + mem_map[i++] = (struct e820_entry) { > > + .addr = BZ_KERNEL_START, > > + .size = KVM_32BIT_GAP_START - BZ_KERNEL_START, > > + .type = E820_MEM_USABLE, > > + }; > > + mem_map[i++] = (struct e820_entry) { > > + .addr = 0x100000000ULL, > > + .size = kvm->ram_size - KVM_32BIT_GAP_START, > > + .type = E820_MEM_USABLE, > > + }; > > + } > > > > BUILD_BUG_ON(i > E820_MEM_AREAS); > > + > > + *size = i; > > } > > > > /** > > diff --git a/tools/kvm/include/kvm/e820.h b/tools/kvm/include/kvm/e820.h > > index 252ae1f..e0f5f2a 100644 > > --- a/tools/kvm/include/kvm/e820.h > > +++ b/tools/kvm/include/kvm/e820.h > > @@ -8,7 +8,7 @@ > > #define E820_MEM_USABLE 1 > > #define E820_MEM_RESERVED 2 > > > > -#define E820_MEM_AREAS 4 > > +#define E820_MEM_AREAS 5 > > > > struct e820_entry { > > u64 addr; /* start of memory segment */ > > diff --git a/tools/kvm/include/kvm/kvm.h b/tools/kvm/include/kvm/kvm.h > > index 3dab78d..5e2e64c 100644 > > --- a/tools/kvm/include/kvm/kvm.h > > +++ b/tools/kvm/include/kvm/kvm.h > > @@ -8,6 +8,8 @@ > > #include <time.h> > > > > #define KVM_NR_CPUS (255) > > +#define KVM_32BIT_GAP_SIZE (512 << 20) > > +#define KVM_32BIT_GAP_START ((1ULL << 32) - KVM_32BIT_GAP_SIZE) > > > > struct kvm { > > int sys_fd; /* For system ioctls(), i.e. /dev/kvm */ > > diff --git a/tools/kvm/kvm.c b/tools/kvm/kvm.c > > index 65793f2..a3d3dd8 100644 > > --- a/tools/kvm/kvm.c > > +++ b/tools/kvm/kvm.c > > @@ -153,23 +153,64 @@ static bool kvm__cpu_supports_vm(void) > > return regs.ecx & (1 << feature); > > } > > > > -void kvm__init_ram(struct kvm *self) > > +static void kvm_register_mem_slot(struct kvm *kvm, u32 slot, u64 guest_phys, u64 size, void *userspace_addr) > > { > > struct kvm_userspace_memory_region mem; > > int ret; > > > > mem = (struct kvm_userspace_memory_region) { > > - .slot = 0, > > - .guest_phys_addr = 0x0UL, > > - .memory_size = self->ram_size, > > - .userspace_addr = (unsigned long) self->ram_start, > > + .slot = slot, > > + .guest_phys_addr = guest_phys, > > + .memory_size = size, > > + .userspace_addr = (u64)userspace_addr, > > > I am seeing: > > CC kvm.o > kvm.c: In function ‘kvm_register_mem_slot’: > kvm.c:165:22: error: cast from pointer to integer of different size > [-Werror=pointer-to-int-cast] > cc1: all warnings being treated as errors > > make: *** [kvm.o] Error 1 > > with this patch on 32-bit box. it's useful if you report the 'gcc -v' output for compiler warnings - so that we can after some time have a mental picture of which GCC versions produce spurious warnings. Btw,. it would also be useful to add a 'make WERROR=0' option - that way warnings that trigger only on some GCC versions can be skipped during the build while they will still be reported to us because the default 'make' fails. [ If you add that then please also send such a patch against tools/perf/ :-) ] Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/tools/kvm/bios.c b/tools/kvm/bios.c index 2199c0c..3cd9b24 100644 --- a/tools/kvm/bios.c +++ b/tools/kvm/bios.c @@ -61,8 +61,6 @@ static void e820_setup(struct kvm *kvm) size = guest_flat_to_host(kvm, E820_MAP_SIZE); mem_map = guest_flat_to_host(kvm, E820_MAP_START); - *size = E820_MEM_AREAS; - mem_map[i++] = (struct e820_entry) { .addr = REAL_MODE_IVT_BEGIN, .size = EBDA_START - REAL_MODE_IVT_BEGIN, @@ -78,13 +76,28 @@ static void e820_setup(struct kvm *kvm) .size = MB_BIOS_END - MB_BIOS_BEGIN, .type = E820_MEM_RESERVED, }; - mem_map[i++] = (struct e820_entry) { - .addr = BZ_KERNEL_START, - .size = kvm->ram_size - BZ_KERNEL_START, - .type = E820_MEM_USABLE, - }; + if (kvm->ram_size < KVM_32BIT_GAP_START) { + mem_map[i++] = (struct e820_entry) { + .addr = BZ_KERNEL_START, + .size = kvm->ram_size - BZ_KERNEL_START, + .type = E820_MEM_USABLE, + }; + } else { + mem_map[i++] = (struct e820_entry) { + .addr = BZ_KERNEL_START, + .size = KVM_32BIT_GAP_START - BZ_KERNEL_START, + .type = E820_MEM_USABLE, + }; + mem_map[i++] = (struct e820_entry) { + .addr = 0x100000000ULL, + .size = kvm->ram_size - KVM_32BIT_GAP_START, + .type = E820_MEM_USABLE, + }; + } BUILD_BUG_ON(i > E820_MEM_AREAS); + + *size = i; } /** diff --git a/tools/kvm/include/kvm/e820.h b/tools/kvm/include/kvm/e820.h index 252ae1f..e0f5f2a 100644 --- a/tools/kvm/include/kvm/e820.h +++ b/tools/kvm/include/kvm/e820.h @@ -8,7 +8,7 @@ #define E820_MEM_USABLE 1 #define E820_MEM_RESERVED 2 -#define E820_MEM_AREAS 4 +#define E820_MEM_AREAS 5 struct e820_entry { u64 addr; /* start of memory segment */ diff --git a/tools/kvm/include/kvm/kvm.h b/tools/kvm/include/kvm/kvm.h index 3dab78d..5e2e64c 100644 --- a/tools/kvm/include/kvm/kvm.h +++ b/tools/kvm/include/kvm/kvm.h @@ -8,6 +8,8 @@ #include <time.h> #define KVM_NR_CPUS (255) +#define KVM_32BIT_GAP_SIZE (512 << 20) +#define KVM_32BIT_GAP_START ((1ULL << 32) - KVM_32BIT_GAP_SIZE) struct kvm { int sys_fd; /* For system ioctls(), i.e. /dev/kvm */ diff --git a/tools/kvm/kvm.c b/tools/kvm/kvm.c index 65793f2..a3d3dd8 100644 --- a/tools/kvm/kvm.c +++ b/tools/kvm/kvm.c @@ -153,23 +153,64 @@ static bool kvm__cpu_supports_vm(void) return regs.ecx & (1 << feature); } -void kvm__init_ram(struct kvm *self) +static void kvm_register_mem_slot(struct kvm *kvm, u32 slot, u64 guest_phys, u64 size, void *userspace_addr) { struct kvm_userspace_memory_region mem; int ret; mem = (struct kvm_userspace_memory_region) { - .slot = 0, - .guest_phys_addr = 0x0UL, - .memory_size = self->ram_size, - .userspace_addr = (unsigned long) self->ram_start, + .slot = slot, + .guest_phys_addr = guest_phys, + .memory_size = size, + .userspace_addr = (u64)userspace_addr, }; - ret = ioctl(self->vm_fd, KVM_SET_USER_MEMORY_REGION, &mem); + ret = ioctl(kvm->vm_fd, KVM_SET_USER_MEMORY_REGION, &mem); if (ret < 0) die_perror("KVM_SET_USER_MEMORY_REGION ioctl"); } +/* + * Allocating RAM size bigger than 4GB requires us to leave a gap + * in the RAM which is used for PCI MMIO, hotplug, and unconfigured + * devices (see documentation of e820_setup_gap() for details). + * + * If we're required to initialize RAM bigger than 4GB, we will create + * a gap between 0xe0000000 and 0x100000000 in the guest virtual mem space. + */ + +void kvm__init_ram(struct kvm *self) +{ + u64 phys_start, phys_size; + void *host_mem; + + if (self->ram_size < KVM_32BIT_GAP_START) { + /* Use a single block of RAM for 32bit RAM */ + + phys_start = 0; + phys_size = self->ram_size; + host_mem = self->ram_start; + + kvm_register_mem_slot(self, 0, 0, self->ram_size, self->ram_start); + } else { + /* First RAM range from zero to the PCI gap: */ + + phys_start = 0; + phys_size = KVM_32BIT_GAP_START; + host_mem = self->ram_start; + + kvm_register_mem_slot(self, 0, phys_start, phys_size, host_mem); + + /* Second RAM range from 4GB to the end of RAM: */ + + phys_start = 0x100000000ULL; + phys_size = self->ram_size - phys_size; + host_mem = self->ram_start + phys_start; + + kvm_register_mem_slot(self, 1, phys_start, phys_size, host_mem); + } +} + int kvm__max_cpus(struct kvm *self) { int ret; @@ -225,7 +266,18 @@ struct kvm *kvm__init(const char *kvm_dev, unsigned long ram_size) self->ram_size = ram_size; - self->ram_start = mmap(NULL, ram_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); + if (self->ram_size < KVM_32BIT_GAP_START) { + self->ram_start = mmap(NULL, ram_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); + } else { + self->ram_start = mmap(NULL, ram_size + KVM_32BIT_GAP_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); + if (self->ram_start != MAP_FAILED) { + /* + * We mprotect the gap (see kvm__init_ram() for details) PROT_NONE so that + * if we accidently write to it, we will know. + */ + mprotect(self->ram_start + KVM_32BIT_GAP_START, KVM_32BIT_GAP_SIZE, PROT_NONE); + } + } if (self->ram_start == MAP_FAILED) die("out of memory");