KVM: report 1GB page support to userspace

If userspace knows that the kernel part supports 1GB pages it can enable
the corresponding cpuid bit so that guests actually use GB pages.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3315efaacf9ea9df9ae73defee56c7d8cd3cfb7b..b17d845897b797fe0f6daa1cb66b968c0e56e1eb 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -528,6 +528,8 @@ struct kvm_x86_ops {
        int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
        int (*get_tdp_level)(void);
        u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
+       bool (*gb_page_enable)(void);
+
        const struct trace_print_flags *exit_reasons_str;
 };
 

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 92fc0dab505d64ac974402e0af888af1dbd94653..10e718db990b11d2ed22da81a523d47d93bf2d00 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2754,6 +2754,11 @@ static const struct trace_print_flags svm_exit_reasons_str[] = {
        { -1, NULL }
 };
 
+static bool svm_gb_page_enable(void)
+{
+       return true;
+}
+
 static struct kvm_x86_ops svm_x86_ops = {
        .cpu_has_kvm_support = has_svm,
        .disabled_by_bios = is_disabled,
@@ -2817,6 +2822,7 @@ static struct kvm_x86_ops svm_x86_ops = {
        .get_mt_mask = svm_get_mt_mask,
 
        .exit_reasons_str = svm_exit_reasons_str,
+       .gb_page_enable = svm_gb_page_enable,
 };
 
 static int __init svm_init(void)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c5aaa1b5fdbed9b53fe8bfe327e39ed0c534e361..32e6d2031ba26d8522d29be13c7656aaf0be3dbc 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3908,6 +3908,11 @@ static const struct trace_print_flags vmx_exit_reasons_str[] = {
        { -1, NULL }
 };
 
+static bool vmx_gb_page_enable(void)
+{
+       return false;
+}
+
 static struct kvm_x86_ops vmx_x86_ops = {
        .cpu_has_kvm_support = cpu_has_kvm_support,
        .disabled_by_bios = vmx_disabled_by_bios,
@@ -3969,6 +3974,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
        .get_mt_mask = vmx_get_mt_mask,
 
        .exit_reasons_str = vmx_exit_reasons_str,
+       .gb_page_enable = vmx_gb_page_enable,
 };
 
 static int __init vmx_init(void)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 69de7248083fc0cb361334a72778ea65aaedab18..fa525d511d9276a0b5d011c600b499ac9dd36860 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1444,6 +1444,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
                         u32 index, int *nent, int maxnent)
 {
        unsigned f_nx = is_efer_nx() ? F(NX) : 0;
+       unsigned f_gbpages = kvm_x86_ops->gb_page_enable() ? F(GBPAGES) : 0;
 #ifdef CONFIG_X86_64
        unsigned f_lm = F(LM);
 #else
@@ -1468,7 +1469,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
                F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
                F(PAT) | F(PSE36) | 0 /* Reserved */ |
                f_nx | 0 /* Reserved */ | F(MMXEXT) | F(MMX) |
-               F(FXSR) | F(FXSR_OPT) | 0 /* GBPAGES */ | 0 /* RDTSCP */ |
+               F(FXSR) | F(FXSR_OPT) | f_gbpages | 0 /* RDTSCP */ |
                0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW);
        /* cpuid 1.ecx */
        const u32 kvm_supported_word4_x86_features =