hw/i386/vmport: Propagate IOPort read to vCPU EAX register
vmport_ioport_read() returns the value that should propagate to vCPU EAX register when guest reads VMPort IOPort (i.e. By x86 IN instruction). However, because vmport_ioport_read() calls cpu_synchronize_state(), the returned value gets overridden by the value in QEMU vCPU EAX register. i.e. cpu->env.regs[R_EAX]. To fix this issue, change vmport_ioport_read() to explicitly override cpu->env.regs[R_EAX] with the value it wish to propagate to vCPU EAX register. Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com> Signed-off-by: Liran Alon <liran.alon@oracle.com> Message-Id: <20200312165431.82118-4-liran.alon@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -43,6 +43,7 @@ GlobalProperty hw_compat_4_2[] = {
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{ "qxl", "revision", "4" },
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{ "qxl", "revision", "4" },
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{ "qxl-vga", "revision", "4" },
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{ "qxl-vga", "revision", "4" },
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{ "fw_cfg", "acpi-mr-restore", "false" },
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{ "fw_cfg", "acpi-mr-restore", "false" },
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{ "vmport", "x-read-set-eax", "off" },
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};
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};
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const size_t hw_compat_4_2_len = G_N_ELEMENTS(hw_compat_4_2);
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const size_t hw_compat_4_2_len = G_N_ELEMENTS(hw_compat_4_2);
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@ -43,6 +43,11 @@
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#define VMPORT_ENTRIES 0x2c
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#define VMPORT_ENTRIES 0x2c
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#define VMPORT_MAGIC 0x564D5868
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#define VMPORT_MAGIC 0x564D5868
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/* Compatibility flags for migration */
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#define VMPORT_COMPAT_READ_SET_EAX_BIT 0
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#define VMPORT_COMPAT_READ_SET_EAX \
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(1 << VMPORT_COMPAT_READ_SET_EAX_BIT)
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#define VMPORT(obj) OBJECT_CHECK(VMPortState, (obj), TYPE_VMPORT)
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#define VMPORT(obj) OBJECT_CHECK(VMPortState, (obj), TYPE_VMPORT)
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typedef struct VMPortState {
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typedef struct VMPortState {
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@ -51,6 +56,8 @@ typedef struct VMPortState {
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MemoryRegion io;
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MemoryRegion io;
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VMPortReadFunc *func[VMPORT_ENTRIES];
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VMPortReadFunc *func[VMPORT_ENTRIES];
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void *opaque[VMPORT_ENTRIES];
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void *opaque[VMPORT_ENTRIES];
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uint32_t compat_flags;
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} VMPortState;
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} VMPortState;
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static VMPortState *port_state;
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static VMPortState *port_state;
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@ -80,17 +87,33 @@ static uint64_t vmport_ioport_read(void *opaque, hwaddr addr,
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eax = env->regs[R_EAX];
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eax = env->regs[R_EAX];
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if (eax != VMPORT_MAGIC) {
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if (eax != VMPORT_MAGIC) {
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return eax;
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goto out;
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}
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}
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command = env->regs[R_ECX];
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command = env->regs[R_ECX];
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trace_vmport_command(command);
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trace_vmport_command(command);
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if (command >= VMPORT_ENTRIES || !s->func[command]) {
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if (command >= VMPORT_ENTRIES || !s->func[command]) {
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qemu_log_mask(LOG_UNIMP, "vmport: unknown command %x\n", command);
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qemu_log_mask(LOG_UNIMP, "vmport: unknown command %x\n", command);
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return eax;
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goto out;
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}
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}
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return s->func[command](s->opaque[command], addr);
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eax = s->func[command](s->opaque[command], addr);
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out:
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/*
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* The call above to cpu_synchronize_state() gets vCPU registers values
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* to QEMU but also cause QEMU to write QEMU vCPU registers values to
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* vCPU implementation (e.g. Accelerator such as KVM) just before
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* resuming guest.
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*
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* Therefore, in order to make IOPort return value propagate to
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* guest EAX, we need to explicitly update QEMU EAX register value.
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*/
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if (s->compat_flags & VMPORT_COMPAT_READ_SET_EAX) {
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cpu->env.regs[R_EAX] = eax;
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}
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return eax;
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}
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}
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static void vmport_ioport_write(void *opaque, hwaddr addr,
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static void vmport_ioport_write(void *opaque, hwaddr addr,
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@ -142,6 +165,9 @@ static void vmport_realizefn(DeviceState *dev, Error **errp)
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}
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}
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static Property vmport_properties[] = {
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static Property vmport_properties[] = {
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/* Used to enforce compatibility for migration */
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DEFINE_PROP_BIT("x-read-set-eax", VMPortState, compat_flags,
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VMPORT_COMPAT_READ_SET_EAX_BIT, true),
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DEFINE_PROP_END_OF_LIST(),
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DEFINE_PROP_END_OF_LIST(),
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};
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};
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