kvm: Fix kernel boot IP

Booting to a Linux kernel is no longer supported.  Therefore, start executing
at offset 0x200 of bzImage which has a jump to real-mode setup code.  See
Documentation/x86/boot.txt for more details.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

diff --git a/tools/kvm/include/kvm/kvm.h b/tools/kvm/include/kvm/kvm.h
index d3f6ac86f801494c827ecc9e38457239a4006316..edec88b8bee566fc2df57dc87cd72a3ef8bbe5e4 100644 (file)
--- a/tools/kvm/include/kvm/kvm.h
+++ b/tools/kvm/include/kvm/kvm.h
@@ -15,6 +15,9 @@ struct kvm {
        uint64_t                ram_size;
        void                    *ram_start;
 
+       uint16_t                boot_cs;
+       uint16_t                boot_ip;
+
        struct kvm_regs         regs;
        struct kvm_sregs        sregs;
 };

diff --git a/tools/kvm/kvm.c b/tools/kvm/kvm.c
index 4214675107913e5021fb010a0c28bceacef5c4d3..d52a0aab6ee934541a8e8a6c8d62059c4f80f25b 100644 (file)
--- a/tools/kvm/kvm.c
+++ b/tools/kvm/kvm.c
@@ -156,7 +156,7 @@ static inline uint32_t segment_to_flat(uint16_t selector, uint16_t offset)
 #define BOOT_LOADER_CS         0x0000
 #define BOOT_LOADER_IP         0x7c00
 
-static int load_flat_binary(struct kvm *kvm, int fd)
+static int load_flat_binary(struct kvm *self, int fd)
 {
        void *p;
        int nr;
@@ -164,11 +164,14 @@ static int load_flat_binary(struct kvm *kvm, int fd)
        if (lseek(fd, 0, SEEK_SET) < 0)
                die_perror("lseek");
 
-       p = guest_addr_to_host(kvm, segment_to_flat(BOOT_LOADER_CS, BOOT_LOADER_IP));
+       p = guest_addr_to_host(self, segment_to_flat(BOOT_LOADER_CS, BOOT_LOADER_IP));
 
        while ((nr = read(fd, p, 65536)) > 0)
                p += nr;
 
+       self->boot_cs           = BOOT_LOADER_CS;
+       self->boot_ip           = BOOT_LOADER_IP;
+
        return true;
 }
 
@@ -182,7 +185,7 @@ static const char *BZIMAGE_MAGIC    = "HdrS";
 
 #define BZ_DEFAULT_SETUP_SECTS         4
 
-static bool load_bzimage(struct kvm *kvm, int fd)
+static bool load_bzimage(struct kvm *self, int fd)
 {
        unsigned long setup_sects;
        struct boot_params boot;
@@ -211,16 +214,23 @@ static bool load_bzimage(struct kvm *kvm, int fd)
                setup_sects      = BZ_DEFAULT_SETUP_SECTS;
 
        setup_size = setup_sects << 9;
-       p = guest_addr_to_host(kvm, segment_to_flat(BOOT_LOADER_CS, BOOT_LOADER_IP));
+       p = guest_addr_to_host(self, segment_to_flat(BOOT_LOADER_CS, BOOT_LOADER_IP));
 
        if (read(fd, p, setup_size) != setup_size)
                die_perror("read");
 
-       p = guest_addr_to_host(kvm, BZ_KERNEL_START);
+       p = guest_addr_to_host(self, BZ_KERNEL_START);
 
        while ((nr = read(fd, p, 65536)) > 0)
                p += nr;
 
+       self->boot_cs           = BOOT_LOADER_CS;
+       /*
+        * The real-mode setup code starts at offset 0x200 of a bzImage. See
+        * Documentation/x86/boot.txt for details.
+        */
+       self->boot_ip           = BOOT_LOADER_IP + 0x200;
+
        return true;
 }
 
@@ -270,8 +280,8 @@ void kvm__reset_vcpu(struct kvm *self)
                         * KVM on Intel requires 'base' to be 'selector * 16' in
                         * real mode.
                         */
-                       .selector       = BOOT_LOADER_CS,
-                       .base           = BOOT_LOADER_CS * 16,
+                       .selector       = self->boot_cs,
+                       .base           = self->boot_cs * 16,
                        .limit          = 0xffffU,
                        .type           = 0x0bU,
                        .present        = 1,
@@ -335,7 +345,7 @@ void kvm__reset_vcpu(struct kvm *self)
                die_perror("KVM_SET_SREGS failed");
 
        self->regs = (struct kvm_regs) {
-               .rip            = BOOT_LOADER_IP,
+               .rip            = self->boot_ip,
                /* We start the guest in 16-bit real mode  */
                .rflags         = 0x0000000000000002ULL,
        };