From 6bdbfe99916398dbb28d83833cc04757110f2738 Mon Sep 17 00:00:00 2001 From: Alok Kataria Date: Mon, 3 Nov 2008 11:31:28 -0800 Subject: [PATCH] x86: VMware: Fix vmware_get_tsc code Impact: Fix possible failure to calibrate the TSC on Vmware near 4 GHz The current version of the code to get the tsc frequency from the VMware hypervisor, will be broken on processor with frequency (4G-1) HZ, because on such processors eax will have UINT_MAX and that would be legitimate. We instead check that EBX did change to decide if we were able to read the frequency from the hypervisor. Signed-off-by: Alok N Kataria Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/vmware.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c index 2ac4394fcb9..a0905ecfe7d 100644 --- a/arch/x86/kernel/cpu/vmware.c +++ b/arch/x86/kernel/cpu/vmware.c @@ -36,7 +36,7 @@ "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) : \ "0"(VMWARE_HYPERVISOR_MAGIC), \ "1"(VMWARE_PORT_CMD_##cmd), \ - "2"(VMWARE_HYPERVISOR_PORT), "3"(0) : \ + "2"(VMWARE_HYPERVISOR_PORT), "3"(UINT_MAX) : \ "memory"); static inline int __vmware_platform(void) @@ -53,7 +53,7 @@ static unsigned long __vmware_get_tsc_khz(void) VMWARE_PORT(GETHZ, eax, ebx, ecx, edx); - if (eax == (uint32_t)-1) + if (ebx == UINT_MAX) return 0; tsc_hz = eax | (((uint64_t)ebx) << 32); do_div(tsc_hz, 1000); -- 2.39.2