From 110761987d10c6e6983cc445618acfd158d7ce02 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Fri, 21 Jan 2011 21:48:18 +0100 Subject: [PATCH] kvm: x86: Rework identity map and TSS setup for larger BIOS sizes In order to support loading BIOSes > 256K, reorder the code, adjusting the base if the kernel supports moving the identity map. Signed-off-by: Jan Kiszka Signed-off-by: Marcelo Tosatti --- target-i386/kvm.c | 63 ++++++++++++++++++++++------------------------- 1 file changed, 30 insertions(+), 33 deletions(-) diff --git a/target-i386/kvm.c b/target-i386/kvm.c index 1db8227db..72f9fdf24 100644 --- a/target-i386/kvm.c +++ b/target-i386/kvm.c @@ -493,27 +493,9 @@ static int kvm_get_supported_msrs(KVMState *s) return ret; } -static int kvm_init_identity_map_page(KVMState *s) -{ -#ifdef KVM_CAP_SET_IDENTITY_MAP_ADDR - int ret; - uint64_t addr = 0xfffbc000; - - if (!kvm_check_extension(s, KVM_CAP_SET_IDENTITY_MAP_ADDR)) { - return 0; - } - - ret = kvm_vm_ioctl(s, KVM_SET_IDENTITY_MAP_ADDR, &addr); - if (ret < 0) { - fprintf(stderr, "kvm_set_identity_map_addr: %s\n", strerror(ret)); - return ret; - } -#endif - return 0; -} - int kvm_arch_init(KVMState *s) { + uint64_t identity_base = 0xfffbc000; int ret; struct utsname utsname; @@ -525,27 +507,42 @@ int kvm_arch_init(KVMState *s) uname(&utsname); lm_capable_kernel = strcmp(utsname.machine, "x86_64") == 0; - /* create vm86 tss. KVM uses vm86 mode to emulate 16-bit code - * directly. In order to use vm86 mode, a TSS is needed. Since this - * must be part of guest physical memory, we need to allocate it. */ - - /* this address is 3 pages before the bios, and the bios should present - * as unavaible memory. FIXME, need to ensure the e820 map deals with - * this? - */ /* - * Tell fw_cfg to notify the BIOS to reserve the range. + * On older Intel CPUs, KVM uses vm86 mode to emulate 16-bit code directly. + * In order to use vm86 mode, an EPT identity map and a TSS are needed. + * Since these must be part of guest physical memory, we need to allocate + * them, both by setting their start addresses in the kernel and by + * creating a corresponding e820 entry. We need 4 pages before the BIOS. + * + * Older KVM versions may not support setting the identity map base. In + * that case we need to stick with the default, i.e. a 256K maximum BIOS + * size. */ - if (e820_add_entry(0xfffbc000, 0x4000, E820_RESERVED) < 0) { - perror("e820_add_entry() table is full"); - exit(1); +#ifdef KVM_CAP_SET_IDENTITY_MAP_ADDR + if (kvm_check_extension(s, KVM_CAP_SET_IDENTITY_MAP_ADDR)) { + /* Allows up to 16M BIOSes. */ + identity_base = 0xfeffc000; + + ret = kvm_vm_ioctl(s, KVM_SET_IDENTITY_MAP_ADDR, &identity_base); + if (ret < 0) { + return ret; + } } - ret = kvm_vm_ioctl(s, KVM_SET_TSS_ADDR, 0xfffbd000); +#endif + /* Set TSS base one page after EPT identity map. */ + ret = kvm_vm_ioctl(s, KVM_SET_TSS_ADDR, identity_base + 0x1000); if (ret < 0) { return ret; } - return kvm_init_identity_map_page(s); + /* Tell fw_cfg to notify the BIOS to reserve the range. */ + ret = e820_add_entry(identity_base, 0x4000, E820_RESERVED); + if (ret < 0) { + fprintf(stderr, "e820_add_entry() table is full\n"); + return ret; + } + + return 0; } static void set_v8086_seg(struct kvm_segment *lhs, const SegmentCache *rhs)