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authorPaolo Bonzini <pbonzini@redhat.com>2023-06-20 16:49:35 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2023-06-29 10:49:43 +0200
commit40a205da415e9c10ff02505078700e14ead77092 (patch)
tree3b55730d2d0541dcecddbcfc39d40e58744a2b4f /linux-user
parentd903259dd2dbe40e007db1724dd072c5e210b3f4 (diff)
downloadqemu-40a205da415e9c10ff02505078700e14ead77092.zip
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target/i386: emulate 64-bit ring 0 for linux-user if LM feature is set
32-bit binaries can run on a long mode processor even if the kernel is 64-bit, of course, and this can have slightly different behavior; for example, SYSCALL is allowed on Intel processors. Allow reporting LM to programs running under user mode emulation, so that "-cpu" can be used with named CPU models even for qemu-i386 and even without disabling LM by hand. Fortunately, most of the runtime code in QEMU has to depend on HF_LMA_MASK or on HF_CS64_MASK (which is anyway false for qemu-i386's 32-bit code segment) rather than TARGET_X86_64, therefore all that is needed is an update of linux-user's ring 0 setup. Fixes: https://gitlab.com/qemu-project/qemu/-/issues/1534 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'linux-user')
-rw-r--r--linux-user/i386/cpu_loop.c57
1 files changed, 27 insertions, 30 deletions
diff --git a/linux-user/i386/cpu_loop.c b/linux-user/i386/cpu_loop.c
index 9eeda55..ef2dcb3 100644
--- a/linux-user/i386/cpu_loop.c
+++ b/linux-user/i386/cpu_loop.c
@@ -47,7 +47,7 @@ static void write_dt(void *ptr, unsigned long addr, unsigned long limit,
}
static uint64_t *idt_table;
-#ifdef TARGET_X86_64
+
static void set_gate64(void *ptr, unsigned int type, unsigned int dpl,
uint64_t addr, unsigned int sel)
{
@@ -60,8 +60,10 @@ static void set_gate64(void *ptr, unsigned int type, unsigned int dpl,
p[2] = tswap32(addr >> 32);
p[3] = 0;
}
+
+#ifdef TARGET_X86_64
/* only dpl matters as we do only user space emulation */
-static void set_idt(int n, unsigned int dpl)
+static void set_idt(int n, unsigned int dpl, bool is64)
{
set_gate64(idt_table + n * 2, 0, dpl, 0, 0);
}
@@ -78,9 +80,13 @@ static void set_gate(void *ptr, unsigned int type, unsigned int dpl,
}
/* only dpl matters as we do only user space emulation */
-static void set_idt(int n, unsigned int dpl)
+static void set_idt(int n, unsigned int dpl, bool is64)
{
- set_gate(idt_table + n, 0, dpl, 0, 0);
+ if (is64) {
+ set_gate64(idt_table + n * 2, 0, dpl, 0, 0);
+ } else {
+ set_gate(idt_table + n, 0, dpl, 0, 0);
+ }
}
#endif
@@ -325,6 +331,9 @@ static void target_cpu_free(void *obj)
void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
{
CPUState *cpu = env_cpu(env);
+ bool is64 = (env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_LM) != 0;
+ int i;
+
OBJECT(cpu)->free = target_cpu_free;
env->cr[0] = CR0_PG_MASK | CR0_WP_MASK | CR0_PE_MASK;
env->hflags |= HF_PE_MASK | HF_CPL_MASK;
@@ -332,15 +341,18 @@ void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
env->cr[4] |= CR4_OSFXSR_MASK;
env->hflags |= HF_OSFXSR_MASK;
}
-#ifndef TARGET_ABI32
+
/* enable 64 bit mode if possible */
- if (!(env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_LM)) {
+ if (is64) {
+ env->cr[4] |= CR4_PAE_MASK;
+ env->efer |= MSR_EFER_LMA | MSR_EFER_LME;
+ env->hflags |= HF_LMA_MASK;
+ }
+#ifndef TARGET_ABI32
+ else {
fprintf(stderr, "The selected x86 CPU does not support 64 bit mode\n");
exit(EXIT_FAILURE);
}
- env->cr[4] |= CR4_PAE_MASK;
- env->efer |= MSR_EFER_LMA | MSR_EFER_LME;
- env->hflags |= HF_LMA_MASK;
#endif
/* flags setup : we activate the IRQs by default as in user mode */
@@ -379,27 +391,12 @@ void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
idt_table = g2h_untagged(env->idt.base);
- set_idt(0, 0);
- set_idt(1, 0);
- set_idt(2, 0);
- set_idt(3, 3);
- set_idt(4, 3);
- set_idt(5, 0);
- set_idt(6, 0);
- set_idt(7, 0);
- set_idt(8, 0);
- set_idt(9, 0);
- set_idt(10, 0);
- set_idt(11, 0);
- set_idt(12, 0);
- set_idt(13, 0);
- set_idt(14, 0);
- set_idt(15, 0);
- set_idt(16, 0);
- set_idt(17, 0);
- set_idt(18, 0);
- set_idt(19, 0);
- set_idt(0x80, 3);
+ for (i = 0; i < 20; i++) {
+ set_idt(i, 0, is64);
+ }
+ set_idt(3, 3, is64);
+ set_idt(4, 3, is64);
+ set_idt(0x80, 3, is64);
/* linux segment setup */
{