From: Sean Christopherson seanjc@google.com
[ Upstream commit 75236f5f2299b502e4b9b267c1ce3bc14a222ceb ]
Return appropriate error codes if setting up the GHCB scratch area for an SEV-ES guest fails. In particular, returning -EINVAL instead of -ENOMEM when allocating the kernel buffer could be confusing as userspace would likely suspect a guest issue.
Fixes: 8f423a80d299 ("KVM: SVM: Support MMIO for an SEV-ES guest") Cc: Tom Lendacky thomas.lendacky@amd.com Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20211109222350.2266045-2-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/svm/sev.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index ca0effb79eab9..134c4ea5e6ad8 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2317,7 +2317,7 @@ void pre_sev_run(struct vcpu_svm *svm, int cpu) }
#define GHCB_SCRATCH_AREA_LIMIT (16ULL * PAGE_SIZE) -static bool setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len) +static int setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len) { struct vmcb_control_area *control = &svm->vmcb->control; struct ghcb *ghcb = svm->ghcb; @@ -2328,14 +2328,14 @@ static bool setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len) scratch_gpa_beg = ghcb_get_sw_scratch(ghcb); if (!scratch_gpa_beg) { pr_err("vmgexit: scratch gpa not provided\n"); - return false; + return -EINVAL; }
scratch_gpa_end = scratch_gpa_beg + len; if (scratch_gpa_end < scratch_gpa_beg) { pr_err("vmgexit: scratch length (%#llx) not valid for scratch address (%#llx)\n", len, scratch_gpa_beg); - return false; + return -EINVAL; }
if ((scratch_gpa_beg & PAGE_MASK) == control->ghcb_gpa) { @@ -2353,7 +2353,7 @@ static bool setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len) scratch_gpa_end > ghcb_scratch_end) { pr_err("vmgexit: scratch area is outside of GHCB shared buffer area (%#llx - %#llx)\n", scratch_gpa_beg, scratch_gpa_end); - return false; + return -EINVAL; }
scratch_va = (void *)svm->ghcb; @@ -2366,18 +2366,18 @@ static bool setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len) if (len > GHCB_SCRATCH_AREA_LIMIT) { pr_err("vmgexit: scratch area exceeds KVM limits (%#llx requested, %#llx limit)\n", len, GHCB_SCRATCH_AREA_LIMIT); - return false; + return -EINVAL; } scratch_va = kzalloc(len, GFP_KERNEL_ACCOUNT); if (!scratch_va) - return false; + return -ENOMEM;
if (kvm_read_guest(svm->vcpu.kvm, scratch_gpa_beg, scratch_va, len)) { /* Unable to copy scratch area from guest */ pr_err("vmgexit: kvm_read_guest for scratch area failed\n");
kfree(scratch_va); - return false; + return -EFAULT; }
/* @@ -2393,7 +2393,7 @@ static bool setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len) svm->ghcb_sa = scratch_va; svm->ghcb_sa_len = len;
- return true; + return 0; }
static void set_ghcb_msr_bits(struct vcpu_svm *svm, u64 value, u64 mask, @@ -2532,10 +2532,10 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) ghcb_set_sw_exit_info_1(ghcb, 0); ghcb_set_sw_exit_info_2(ghcb, 0);
- ret = -EINVAL; switch (exit_code) { case SVM_VMGEXIT_MMIO_READ: - if (!setup_vmgexit_scratch(svm, true, control->exit_info_2)) + ret = setup_vmgexit_scratch(svm, true, control->exit_info_2); + if (ret) break;
ret = kvm_sev_es_mmio_read(vcpu, @@ -2544,7 +2544,8 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) svm->ghcb_sa); break; case SVM_VMGEXIT_MMIO_WRITE: - if (!setup_vmgexit_scratch(svm, false, control->exit_info_2)) + ret = setup_vmgexit_scratch(svm, false, control->exit_info_2); + if (ret) break;
ret = kvm_sev_es_mmio_write(vcpu, @@ -2587,6 +2588,7 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) vcpu_unimpl(vcpu, "vmgexit: unsupported event - exit_info_1=%#llx, exit_info_2=%#llx\n", control->exit_info_1, control->exit_info_2); + ret = -EINVAL; break; default: ret = svm_invoke_exit_handler(vcpu, exit_code); @@ -2599,6 +2601,7 @@ int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in) { int count; int bytes; + int r;
if (svm->vmcb->control.exit_info_2 > INT_MAX) return -EINVAL; @@ -2607,8 +2610,9 @@ int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in) if (unlikely(check_mul_overflow(count, size, &bytes))) return -EINVAL;
- if (!setup_vmgexit_scratch(svm, in, bytes)) - return -EINVAL; + r = setup_vmgexit_scratch(svm, in, bytes); + if (r) + return r;
return kvm_sev_es_string_io(&svm->vcpu, size, port, svm->ghcb_sa, count, in); }