From c3d74acf55696107c6e9238e952e4a5240b7b130 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 28 Sep 2017 12:05:53 +0200 Subject: [PATCH] x86: add new Xen cpuid node for max address width info On very large hosts a pv-guest needs to know whether it will have to handle frame numbers larger than 32 bits in order to select the appropriate grant interface version. Add a new Xen specific CPUID node to contain the maximum machine address width similar to the x86 CPUID node 0x80000008 containing the maximum physical address width. The maximum frame width needs to take memory hotplug into account. Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich --- xen/arch/x86/traps.c | 7 +++++++ xen/include/public/arch-x86/cpuid.h | 12 +++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index d8feef2942..86506f3747 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -930,6 +930,13 @@ void cpuid_hypervisor_leaves(const struct vcpu *v, uint32_t leaf, res->b = v->vcpu_id; break; + case 5: /* PV-specific parameters */ + if ( is_hvm_domain(d) || subleaf != 0 ) + break; + + res->b = flsl(get_upper_mfn_bound()) + PAGE_SHIFT; + break; + default: ASSERT_UNREACHABLE(); } diff --git a/xen/include/public/arch-x86/cpuid.h b/xen/include/public/arch-x86/cpuid.h index d709340f18..1c026f7f24 100644 --- a/xen/include/public/arch-x86/cpuid.h +++ b/xen/include/public/arch-x86/cpuid.h @@ -85,6 +85,16 @@ #define XEN_HVM_CPUID_IOMMU_MAPPINGS (1u << 2) #define XEN_HVM_CPUID_VCPU_ID_PRESENT (1u << 3) /* vcpu id is present in EBX */ -#define XEN_CPUID_MAX_NUM_LEAVES 4 +/* + * Leaf 6 (0x40000x05) + * PV-specific parameters + * Sub-leaf 0: EAX: max available sub-leaf + * Sub-leaf 0: EBX: bits 0-7: max machine address width + */ + +/* Max. address width in bits taking memory hotplug into account. */ +#define XEN_CPUID_MACHINE_ADDRESS_WIDTH_MASK (0xffu << 0) + +#define XEN_CPUID_MAX_NUM_LEAVES 5 #endif /* __XEN_PUBLIC_ARCH_X86_CPUID_H__ */ -- 2.30.2