| Message ID | 1305109881-11189-1-git-send-email-levinsasha928@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
* Sasha Levin <levinsasha928@gmail.com> wrote: > } > > +void kvm__init_ram(struct kvm *self) > +{ Why is there no comment explaining what this function does and what the whole gap logic is about? The bug this problem caused was non-obvious, so any future developer reading this code will wonder what this is all about. > + if (self->ram_size < KVM_32BIT_GAP_START) { > + kvm_register_mem_slot(self, 0, 0, self->ram_size, self->ram_start); > + } else { > + kvm_register_mem_slot(self, 0, 0, KVM_32BIT_GAP_START, self->ram_start); > + kvm_register_mem_slot(self, 1, 0x100000000ULL, self->ram_size - KVM_32BIT_GAP_START, self->ram_start + 0x100000000ULL); > + } > +} Why not write it in a much more obvious and almost self-documenting way: /* 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); ? Btw., could we please also stop using 'self' for function parameters? It's utterly meaningless as a name and makes grepping pretty hard. Use a consistent and meaningful convention please, such as: struct kvm_cpu *vcpu And obviously CPU related methods will always have a vcpu parameter around. 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 5/11/11 2:13 PM, Ingo Molnar wrote: > Btw., could we please also stop using 'self' for function parameters? It's > utterly meaningless as a name and makes grepping pretty hard. I blame perf! But sure we can do that. 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
* Pekka Enberg <penberg@cs.helsinki.fi> wrote: > On 5/11/11 2:13 PM, Ingo Molnar wrote: > >Btw., could we please also stop using 'self' for function parameters? It's > >utterly meaningless as a name and makes grepping pretty hard. > > I blame perf! But sure we can do that. The blame is well put - we eliminated almost all instances of 'self' from perf, but somewhat sadly not all of them. This was a brief infection perf caught - but it's highly contagious it appears! 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..16d91d5 100644 --- a/tools/kvm/kvm.c +++ b/tools/kvm/kvm.c @@ -153,23 +153,33 @@ 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"); } +void kvm__init_ram(struct kvm *self) +{ + if (self->ram_size < KVM_32BIT_GAP_START) { + kvm_register_mem_slot(self, 0, 0, self->ram_size, self->ram_start); + } else { + kvm_register_mem_slot(self, 0, 0, KVM_32BIT_GAP_START, self->ram_start); + kvm_register_mem_slot(self, 1, 0x100000000ULL, self->ram_size - KVM_32BIT_GAP_START, self->ram_start + 0x100000000ULL); + } +} + int kvm__max_cpus(struct kvm *self) { int ret; @@ -225,7 +235,13 @@ 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) + mprotect(self->ram_start + KVM_32BIT_GAP_START, KVM_32BIT_GAP_SIZE, PROT_NONE); + } if (self->ram_start == MAP_FAILED) die("out of memory");
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. 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 | 30 +++++++++++++++++++++++------- 4 files changed, 46 insertions(+), 15 deletions(-)