This fixes Spectre-v1/L1TF vulnerabilities in vmx_read_guest_seg_selector(), vmx_read_guest_seg_base(), vmx_read_guest_seg_limit() and vmx_read_guest_seg_ar(). These functions contain index computations based on the (attacker-influenced) segment value.

Fixes: commit 2fb92db1ec08 ("KVM: VMX: Cache vmcs segment fields")

Signed-off-by: Nick Finco nifi@google.com Signed-off-by: Marios Pomonis pomonis@google.com Reviewed-by: Andrew Honig ahonig@google.com Cc: stable@vger.kernel.org --- arch/x86/kvm/vmx/vmx.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index d39475e2d44e..82b25f1812aa 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -753,7 +753,9 @@ static bool vmx_segment_cache_test_set(struct vcpu_vmx *vmx, unsigned seg,

static u16 vmx_read_guest_seg_selector(struct vcpu_vmx *vmx, unsigned seg) { - u16 *p = &vmx->segment_cache.seg[seg].selector; + size_t size = ARRAY_SIZE(vmx->segment_cache.seg); + size_t index = array_index_nospec(seg, size); + u16 *p = &vmx->segment_cache.seg[index].selector;

if (!vmx_segment_cache_test_set(vmx, seg, SEG_FIELD_SEL)) *p = vmcs_read16(kvm_vmx_segment_fields[seg].selector); @@ -762,7 +764,9 @@ static u16 vmx_read_guest_seg_selector(struct vcpu_vmx *vmx, unsigned seg)

static ulong vmx_read_guest_seg_base(struct vcpu_vmx *vmx, unsigned seg) { - ulong *p = &vmx->segment_cache.seg[seg].base; + size_t size = ARRAY_SIZE(vmx->segment_cache.seg); + size_t index = array_index_nospec(seg, size); + ulong *p = &vmx->segment_cache.seg[index].base;

if (!vmx_segment_cache_test_set(vmx, seg, SEG_FIELD_BASE)) *p = vmcs_readl(kvm_vmx_segment_fields[seg].base); @@ -771,7 +775,9 @@ static ulong vmx_read_guest_seg_base(struct vcpu_vmx *vmx, unsigned seg)

static u32 vmx_read_guest_seg_limit(struct vcpu_vmx *vmx, unsigned seg) { - u32 *p = &vmx->segment_cache.seg[seg].limit; + size_t size = ARRAY_SIZE(vmx->segment_cache.seg); + size_t index = array_index_nospec(seg, size); + u32 *p = &vmx->segment_cache.seg[index].limit;

if (!vmx_segment_cache_test_set(vmx, seg, SEG_FIELD_LIMIT)) *p = vmcs_read32(kvm_vmx_segment_fields[seg].limit); @@ -780,7 +786,9 @@ static u32 vmx_read_guest_seg_limit(struct vcpu_vmx *vmx, unsigned seg)

static u32 vmx_read_guest_seg_ar(struct vcpu_vmx *vmx, unsigned seg) { - u32 *p = &vmx->segment_cache.seg[seg].ar; + size_t size = ARRAY_SIZE(vmx->segment_cache.seg); + size_t index = array_index_nospec(seg, size); + u32 *p = &vmx->segment_cache.seg[index].ar;

if (!vmx_segment_cache_test_set(vmx, seg, SEG_FIELD_AR)) *p = vmcs_read32(kvm_vmx_segment_fields[seg].ar_bytes);