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i386: implement IGNNE 

Change the handling of port F0h writes and FPU exceptions to implement IGNNE.

The implementation mixes a bit what the chipset and processor do in real
hardware, but the effect is the same as what happens with actual FERR#
and IGNNE# pins: writing to port F0h asserts IGNNE# in addition to lowering
FP_IRQ; while clearing the SE bit in the FPU status word deasserts IGNNE#.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2019-10-16 10:34:39 +02:00
parent 5caa1833d2
commit bf13bfab08
3 changed files with 31 additions and 9 deletions
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2
hw/i386/pc.c
View File

@ -385,7 +385,7 @@ static void ioportF0_write(void *opaque, hwaddr addr, uint64_t data,
unsigned size)
{
if (tcg_enabled()) {
cpu_clear_ferr();
cpu_set_ignne();
}
}

4
target/i386/cpu.h
View File

@ -203,6 +203,7 @@ typedef enum X86Seg {
#define HF2_SMM_INSIDE_NMI_SHIFT 4 /* CPU serving SMI nested inside NMI */
#define HF2_MPX_PR_SHIFT 5 /* BNDCFGx.BNDPRESERVE */
#define HF2_NPT_SHIFT 6 /* Nested Paging enabled */
#define HF2_IGNNE_SHIFT 7 /* Ignore CR0.NE=0 */
#define HF2_GIF_MASK (1 << HF2_GIF_SHIFT)
#define HF2_HIF_MASK (1 << HF2_HIF_SHIFT)
@ -211,6 +212,7 @@ typedef enum X86Seg {
#define HF2_SMM_INSIDE_NMI_MASK (1 << HF2_SMM_INSIDE_NMI_SHIFT)
#define HF2_MPX_PR_MASK (1 << HF2_MPX_PR_SHIFT)
#define HF2_NPT_MASK (1 << HF2_NPT_SHIFT)
#define HF2_IGNNE_MASK (1 << HF2_IGNNE_SHIFT)
#define CR0_PE_SHIFT 0
#define CR0_MP_SHIFT 1
@ -1762,7 +1764,7 @@ int cpu_x86_support_mca_broadcast(CPUX86State *env);
int cpu_get_pic_interrupt(CPUX86State *s);
/* MSDOS compatibility mode FPU exception support */
void x86_register_ferr_irq(qemu_irq irq);
void cpu_clear_ferr(void);
void cpu_set_ignne(void);
/* mpx_helper.c */
void cpu_sync_bndcs_hflags(CPUX86State *env);

34
target/i386/fpu_helper.c
View File

@ -70,14 +70,24 @@ void x86_register_ferr_irq(qemu_irq irq)
ferr_irq = irq;
}
void cpu_clear_ferr(void)
static void cpu_clear_ignne(void)
{
qemu_irq_lower(ferr_irq);
CPUX86State *env = &X86_CPU(first_cpu)->env;
env->hflags2 &= ~HF2_IGNNE_MASK;
}
static void cpu_set_ferr(void)
void cpu_set_ignne(void)
{
qemu_irq_raise(ferr_irq);
CPUX86State *env = &X86_CPU(first_cpu)->env;
env->hflags2 |= HF2_IGNNE_MASK;
/*
* We get here in response to a write to port F0h. The chipset should
* deassert FP_IRQ and FERR# instead should stay signaled until FPSW_SE is
* cleared, because FERR# and FP_IRQ are two separate pins on real
* hardware. However, we don't model FERR# as a qemu_irq, so we just
* do directly what the chipset would do, i.e. deassert FP_IRQ.
*/
qemu_irq_lower(ferr_irq);
}
#endif
@ -160,8 +170,8 @@ static void fpu_raise_exception(CPUX86State *env, uintptr_t retaddr)
raise_exception_ra(env, EXCP10_COPR, retaddr);
}
#if !defined(CONFIG_USER_ONLY)
else {
cpu_set_ferr();
else if (ferr_irq && !(env->hflags2 & HF2_IGNNE_MASK)) {
qemu_irq_raise(ferr_irq);
}
#endif
}
@ -1056,7 +1066,17 @@ void helper_fstenv(CPUX86State *env, target_ulong ptr, int data32)
static void cpu_set_fpus(CPUX86State *env, uint16_t fpus)
{
env->fpstt = (fpus >> 11) & 7;
env->fpus = fpus & ~0x3800;
env->fpus = fpus & ~0x3800 & ~FPUS_B;
env->fpus |= env->fpus & FPUS_SE ? FPUS_B : 0;
#if !defined(CONFIG_USER_ONLY)
if (!(env->fpus & FPUS_SE)) {
/*
* Here the processor deasserts FERR#; in response, the chipset deasserts
* IGNNE#.
*/
cpu_clear_ignne();
}
#endif
}
static void do_fldenv(CPUX86State *env, target_ulong ptr, int data32,