kvm/svm: PKU not currently supported

commit a47970ed74a535b1accb4bc73643fd5a93993c3e upstream.

Current SVM implementation does not have support for handling PKU. Guests
running on a host with future AMD cpus that support the feature will read
garbage from the PKRU register and will hit segmentation faults on boot as
memory is getting marked as protected that should not be. Ensure that cpuid
from SVM does not advertise the feature.

Signed-off-by: John Allen <john.allen@amd.com>
Cc: stable@vger.kernel.org
Fixes: 0556cbdc2fbc ("x86/pkeys: Don't check if PKRU is zero before writing it")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b79cd6aa4075636d5aac64315a3eba80b7727a90..4a9d869465ad902e8628b2a2bd7076e3dbff691c 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1145,6 +1145,7 @@ struct kvm_x86_ops {
        bool (*xsaves_supported)(void);
        bool (*umip_emulated)(void);
        bool (*pt_supported)(void);
+       bool (*pku_supported)(void);
 
        int (*check_nested_events)(struct kvm_vcpu *vcpu, bool external_intr);
        void (*request_immediate_exit)(struct kvm_vcpu *vcpu);

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index cf55629ff0ff642ea85fb5783f2fd4df678b9d7c..50678fe6a504deacdf1d98d31806fe7380403abc 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -352,6 +352,7 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
        unsigned f_umip = kvm_x86_ops->umip_emulated() ? F(UMIP) : 0;
        unsigned f_intel_pt = kvm_x86_ops->pt_supported() ? F(INTEL_PT) : 0;
        unsigned f_la57;
+       unsigned f_pku = kvm_x86_ops->pku_supported() ? F(PKU) : 0;
 
        /* cpuid 7.0.ebx */
        const u32 kvm_cpuid_7_0_ebx_x86_features =
@@ -363,7 +364,7 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
 
        /* cpuid 7.0.ecx*/
        const u32 kvm_cpuid_7_0_ecx_x86_features =
-               F(AVX512VBMI) | F(LA57) | F(PKU) | 0 /*OSPKE*/ | F(RDPID) |
+               F(AVX512VBMI) | F(LA57) | 0 /*PKU*/ | 0 /*OSPKE*/ | F(RDPID) |
                F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) |
                F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) |
                F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/;
@@ -392,6 +393,7 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
                /* Set LA57 based on hardware capability. */
                entry->ecx |= f_la57;
                entry->ecx |= f_umip;
+               entry->ecx |= f_pku;
                /* PKU is not yet implemented for shadow paging. */
                if (!tdp_enabled || !boot_cpu_has(X86_FEATURE_OSPKE))
                        entry->ecx &= ~F(PKU);

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 122d4ce3b1ab055d1e7fae7ebb4745382d3346b4..8b0620f3aed67363ab805ee66a2b030dce08235e 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6001,6 +6001,11 @@ static bool svm_has_wbinvd_exit(void)
        return true;
 }
 
+static bool svm_pku_supported(void)
+{
+       return false;
+}
+
 #define PRE_EX(exit)  { .exit_code = (exit), \
                        .stage = X86_ICPT_PRE_EXCEPT, }
 #define POST_EX(exit) { .exit_code = (exit), \
@@ -7341,6 +7346,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
        .xsaves_supported = svm_xsaves_supported,
        .umip_emulated = svm_umip_emulated,
        .pt_supported = svm_pt_supported,
+       .pku_supported = svm_pku_supported,
 
        .set_supported_cpuid = svm_set_supported_cpuid,
 

diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 7aa69716d5160421c388154d83db11e15a494606..283bdb7071af604453e081f30baec3bcdd938dac 100644 (file)
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -145,6 +145,11 @@ static inline bool vmx_umip_emulated(void)
                SECONDARY_EXEC_DESC;
 }
 
+static inline bool vmx_pku_supported(void)
+{
+       return boot_cpu_has(X86_FEATURE_PKU);
+}
+
 static inline bool cpu_has_vmx_rdtscp(void)
 {
        return vmcs_config.cpu_based_2nd_exec_ctrl &

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e3394c839dea60a13254e666c446a1237fe8e245..6ba72440b3e32de7614003e2f0816e107bd38215 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7870,6 +7870,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
        .xsaves_supported = vmx_xsaves_supported,
        .umip_emulated = vmx_umip_emulated,
        .pt_supported = vmx_pt_supported,
+       .pku_supported = vmx_pku_supported,
 
        .request_immediate_exit = vmx_request_immediate_exit,