[kvm-commits] [PATCH] kvm: libkvm: kvm_show_code() for ROM code

[Avi Kivity]

From: Jan Kiszka <[EMAIL PROTECTED]>

Userland-located memory is not unconditionally available via
kvm->physical_memory + guest_address. To let kvm_show_code also dump
useful information when, e.g., some problem in ROM (BIOS...) occurs,
this patch tries to obtain the memory content via the mmio_read
callback. If the callback fails, the code byte is marked as invalid.

This patch also removes the check for protected mode and dumps the code
in any case - I didn't find the reason for this restriction.

Signed-off-by: Jan Kiszka <[EMAIL PROTECTED]>
Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>

diff --git a/libkvm/libkvm-x86.c b/libkvm/libkvm-x86.c
index 28efeee..d46fdcc 100644
--- a/libkvm/libkvm-x86.c
+++ b/libkvm/libkvm-x86.c
@@ -393,14 +393,14 @@ int kvm_set_pit(kvm_context_t kvm, struct kvm_pit_state 
*s)
 
 void kvm_show_code(kvm_context_t kvm, int vcpu)
 {
-#define CR0_PE_MASK    (1ULL<<0)
+#define SHOW_CODE_LEN 50
        int fd = kvm->vcpu_fd[vcpu];
        struct kvm_regs regs;
        struct kvm_sregs sregs;
-       int r;
-       unsigned char code[50];
+       int r, n;
        int back_offset;
-       char code_str[sizeof(code) * 3 + 1];
+       unsigned char code;
+       char code_str[SHOW_CODE_LEN * 3 + 1];
        unsigned long rip;
 
        r = ioctl(fd, KVM_GET_SREGS, &sregs);
@@ -408,9 +408,6 @@ void kvm_show_code(kvm_context_t kvm, int vcpu)
                perror("KVM_GET_SREGS");
                return;
        }
-       if (sregs.cr0 & CR0_PE_MASK)
-               return;
-
        r = ioctl(fd, KVM_GET_REGS, &regs);
        if (r == -1) {
                perror("KVM_GET_REGS");
@@ -420,12 +417,16 @@ void kvm_show_code(kvm_context_t kvm, int vcpu)
        back_offset = regs.rip;
        if (back_offset > 20)
            back_offset = 20;
-       memcpy(code, kvm->physical_memory + rip - back_offset, sizeof code);
        *code_str = 0;
-       for (r = 0; r < sizeof code; ++r) {
-               if (r == back_offset)
+       for (n = -back_offset; n < SHOW_CODE_LEN-back_offset; ++n) {
+               if (n == 0)
                        strcat(code_str, " -->");
-               sprintf(code_str + strlen(code_str), " %02x", code[r]);
+               r = kvm->callbacks->mmio_read(kvm->opaque, rip + n, &code, 1);
+               if (r < 0) {
+                       strcat(code_str, " xx");
+                       continue;
+               }
+               sprintf(code_str + strlen(code_str), " %02x", code);
        }
        fprintf(stderr, "code:%s\n", code_str);
 }

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