From 0d045d65c19ac48b31344b566cbf82a0270e6e44 Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Mon, 9 Jan 2017 13:17:01 +0000 Subject: [PATCH] tools/libxc: Fix the reported max_leaf values for PV guests When iterating through CPUID leaves to generating a policy, libxc will clip itself at the hardcoded maxima, meaning that no data outside of the hardcoded maxima are provided to Xen (in turn, causing Xen to return zeros if these leaves are requested.) The HVM code also clips the max_leaf data reported to the guest, but the PV side didn't. This results in a PV guest using the emulated CPUID, or via Xen using CPUID faulting, to observe a max_leaf higher than the toolstack wants, although with zeros being returned in the intervening leaves. Fix the PV side to behave like the HVM side, and clip the max_leaf values in leaf 0 and 0x80000000. Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich Acked-by: Wei Liu --- tools/libxc/xc_cpuid_x86.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/tools/libxc/xc_cpuid_x86.c b/tools/libxc/xc_cpuid_x86.c index e9e3691366..b32001b3fa 100644 --- a/tools/libxc/xc_cpuid_x86.c +++ b/tools/libxc/xc_cpuid_x86.c @@ -615,6 +615,11 @@ static void xc_cpuid_pv_policy(xc_interface *xch, { switch ( input[0] ) { + case 0x00000000: + if ( regs[0] > DEF_MAX_BASE ) + regs[0] = DEF_MAX_BASE; + break; + case 0x00000001: { /* Host topology exposed to PV guest. Provide host value. */ @@ -655,6 +660,16 @@ static void xc_cpuid_pv_policy(xc_interface *xch, xc_cpuid_config_xsave(xch, info, input, regs); break; + case 0x80000000: + { + unsigned int max = info->vendor == VENDOR_AMD + ? DEF_MAX_AMDEXT : DEF_MAX_INTELEXT; + + if ( regs[0] > max ) + regs[0] = max; + break; + } + case 0x80000001: { /* Host topology exposed to PV guest. Provide host CMP_LEGACY value. */ -- 2.30.2