From fe2b201b3be91575857227da7ef21f661bc460b1 Mon Sep 17 00:00:00 2001 From: Bandan Das Date: Mon, 21 Apr 2014 15:20:14 -0400 Subject: [PATCH] KVM: x86: Check for host supported fields in shadow vmcs We track shadow vmcs fields through two static lists, one for read only and another for r/w fields. However, with addition of new vmcs fields, not all fields may be supported on all hosts. If so, copy_vmcs12_to_shadow() trying to vmwrite on unsupported hosts will result in a vmwrite error. For example, commit 36be0b9deb23161 introduced GUEST_BNDCFGS, which is not supported by all processors. Filter out host unsupported fields before letting guests use shadow vmcs Signed-off-by: Bandan Das Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 53 +++++++++++++++++++++++++++++++++++----------- 1 file changed, 41 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 1f68c5831924..33e8c028842f 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -503,7 +503,7 @@ static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu) [number##_HIGH] = VMCS12_OFFSET(name)+4 -static const unsigned long shadow_read_only_fields[] = { +static unsigned long shadow_read_only_fields[] = { /* * We do NOT shadow fields that are modified when L0 * traps and emulates any vmx instruction (e.g. VMPTRLD, @@ -526,10 +526,10 @@ static const unsigned long shadow_read_only_fields[] = { GUEST_LINEAR_ADDRESS, GUEST_PHYSICAL_ADDRESS }; -static const int max_shadow_read_only_fields = +static int max_shadow_read_only_fields = ARRAY_SIZE(shadow_read_only_fields); -static const unsigned long shadow_read_write_fields[] = { +static unsigned long shadow_read_write_fields[] = { GUEST_RIP, GUEST_RSP, GUEST_CR0, @@ -558,7 +558,7 @@ static const unsigned long shadow_read_write_fields[] = { HOST_FS_SELECTOR, HOST_GS_SELECTOR }; -static const int max_shadow_read_write_fields = +static int max_shadow_read_write_fields = ARRAY_SIZE(shadow_read_write_fields); static const unsigned short vmcs_field_to_offset_table[] = { @@ -3009,6 +3009,41 @@ static void free_kvm_area(void) } } +static void init_vmcs_shadow_fields(void) +{ + int i, j; + + /* No checks for read only fields yet */ + + for (i = j = 0; i < max_shadow_read_write_fields; i++) { + switch (shadow_read_write_fields[i]) { + case GUEST_BNDCFGS: + if (!vmx_mpx_supported()) + continue; + break; + default: + break; + } + + if (j < i) + shadow_read_write_fields[j] = + shadow_read_write_fields[i]; + j++; + } + max_shadow_read_write_fields = j; + + /* shadowed fields guest access without vmexit */ + for (i = 0; i < max_shadow_read_write_fields; i++) { + clear_bit(shadow_read_write_fields[i], + vmx_vmwrite_bitmap); + clear_bit(shadow_read_write_fields[i], + vmx_vmread_bitmap); + } + for (i = 0; i < max_shadow_read_only_fields; i++) + clear_bit(shadow_read_only_fields[i], + vmx_vmread_bitmap); +} + static __init int alloc_kvm_area(void) { int cpu; @@ -3039,6 +3074,8 @@ static __init int hardware_setup(void) enable_vpid = 0; if (!cpu_has_vmx_shadow_vmcs()) enable_shadow_vmcs = 0; + if (enable_shadow_vmcs) + init_vmcs_shadow_fields(); if (!cpu_has_vmx_ept() || !cpu_has_vmx_ept_4levels()) { @@ -8803,14 +8840,6 @@ static int __init vmx_init(void) memset(vmx_vmread_bitmap, 0xff, PAGE_SIZE); memset(vmx_vmwrite_bitmap, 0xff, PAGE_SIZE); - /* shadowed read/write fields */ - for (i = 0; i < max_shadow_read_write_fields; i++) { - clear_bit(shadow_read_write_fields[i], vmx_vmwrite_bitmap); - clear_bit(shadow_read_write_fields[i], vmx_vmread_bitmap); - } - /* shadowed read only fields */ - for (i = 0; i < max_shadow_read_only_fields; i++) - clear_bit(shadow_read_only_fields[i], vmx_vmread_bitmap); /* * Allow direct access to the PC debug port (it is often used for I/O