On 03/28/17 23:03, Petr Berky wrote: > It was found qemu_get_present_cpus_count may return impossible > number of cpus because of not checking if fw_cfg exists before > using it. That may lead to undefined behavior of emulator, > in particular Bochs that freezes. > > Signed-off-by: Petr Berky <[email protected]> > --- > src/fw/paravirt.c | 12 +++++++++++- > src/fw/paravirt.h | 1 + > 2 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/src/fw/paravirt.c b/src/fw/paravirt.c > index 707502d..5b23d78 100644 > --- a/src/fw/paravirt.c > +++ b/src/fw/paravirt.c > @@ -32,9 +32,16 @@ u32 RamSize; > u64 RamSizeOver4G; > // Type of emulator platform. > int PlatformRunningOn VARFSEG; > +// cfg enabled > +int cfg_enabled = 0; > // cfg_dma enabled > int cfg_dma_enabled = 0; > > +inline int qemu_cfg_enabled(void) > +{ > + return cfg_enabled; > +} > + > inline int qemu_cfg_dma_enabled(void) > { > return cfg_dma_enabled; > @@ -392,7 +399,9 @@ u16 > qemu_get_present_cpus_count(void) > { > u16 smp_count = 0; > - qemu_cfg_read_entry(&smp_count, QEMU_CFG_NB_CPUS, sizeof(smp_count)); > + if (qemu_cfg_enabled()) { > + qemu_cfg_read_entry(&smp_count, QEMU_CFG_NB_CPUS, sizeof(smp_count)); > + } > u16 cmos_cpu_count = rtc_read(CMOS_BIOS_SMP_COUNT) + 1; > if (smp_count < cmos_cpu_count) { > smp_count = cmos_cpu_count; > @@ -571,6 +580,7 @@ void qemu_cfg_init(void) > return; > > dprintf(1, "Found QEMU fw_cfg\n"); > + cfg_enabled = 1; > > // Detect DMA interface. > u32 id; > diff --git a/src/fw/paravirt.h b/src/fw/paravirt.h > index 16f3d9a..a14d83e 100644 > --- a/src/fw/paravirt.h > +++ b/src/fw/paravirt.h > @@ -49,6 +49,7 @@ static inline int runningOnKVM(void) { > // QEMU_CFG_DMA ID bit > #define QEMU_CFG_VERSION_DMA 2 > > +int qemu_cfg_enabled(void); > int qemu_cfg_dma_enabled(void); > void qemu_preinit(void); > void qemu_platform_setup(void); >
Reviewed-by: Laszlo Ersek <[email protected]> _______________________________________________ SeaBIOS mailing list [email protected] https://www.coreboot.org/mailman/listinfo/seabios
