From 5fbf246bdb9c1ee3f474d3f343e2a79db060c93c Mon Sep 17 00:00:00 2001 From: Petr Berky Date: Tue, 28 Mar 2017 23:03:53 +0200 Subject: config: Add function to check if fw_cfg exists 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 --- src/fw/paravirt.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'src/fw/paravirt.c') diff --git a/src/fw/paravirt.c b/src/fw/paravirt.c index 707502da..5b23d786 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; -- cgit