2021-07-29 13:48:05

by David Edmondson

Subject: [PATCH v3 3/3] KVM: x86: SGX must obey the KVM_INTERNAL_ERROR_EMULATION protocol

When passing the failing address and size out to user space, SGX must
ensure not to trample on the earlier fields of the emulation_failure
sub-union of struct kvm_run.

Signed-off-by: David Edmondson <[email protected]>
---
arch/x86/kvm/vmx/sgx.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
index 6693ebdc0770..63fb93163383 100644
--- a/arch/x86/kvm/vmx/sgx.c
+++ b/arch/x86/kvm/vmx/sgx.c
@@ -53,11 +53,9 @@ static int sgx_get_encls_gva(struct kvm_vcpu *vcpu, unsigned long offset,
static void sgx_handle_emulation_failure(struct kvm_vcpu *vcpu, u64 addr,
unsigned int size)
{
- vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
- vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
- vcpu->run->internal.ndata = 2;
- vcpu->run->internal.data[0] = addr;
- vcpu->run->internal.data[1] = size;
+ uint64_t data[2] = { addr, size };
+
+ kvm_prepare_emulation_failure_exit(vcpu, false, data, sizeof(data));
}

static int sgx_read_hva(struct kvm_vcpu *vcpu, unsigned long hva, void *data,
--
2.30.2

2021-07-30 22:19:34

by Sean Christopherson

Subject: Re: [PATCH v3 3/3] KVM: x86: SGX must obey the KVM_INTERNAL_ERROR_EMULATION protocol

On Thu, Jul 29, 2021, David Edmondson wrote:
> When passing the failing address and size out to user space, SGX must
> ensure not to trample on the earlier fields of the emulation_failure
> sub-union of struct kvm_run.
>
> Signed-off-by: David Edmondson <[email protected]>
> ---
> arch/x86/kvm/vmx/sgx.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
> index 6693ebdc0770..63fb93163383 100644
> --- a/arch/x86/kvm/vmx/sgx.c
> +++ b/arch/x86/kvm/vmx/sgx.c
> @@ -53,11 +53,9 @@ static int sgx_get_encls_gva(struct kvm_vcpu *vcpu, unsigned long offset,
> static void sgx_handle_emulation_failure(struct kvm_vcpu *vcpu, u64 addr,
> unsigned int size)
> {
> - vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> - vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
> - vcpu->run->internal.ndata = 2;
> - vcpu->run->internal.data[0] = addr;
> - vcpu->run->internal.data[1] = size;
> + uint64_t data[2] = { addr, size };
> +
> + kvm_prepare_emulation_failure_exit(vcpu, false, data, sizeof(data));

Assuming we go with my suggestion to have kvm_prepare_emulation_failure_exit()
capture the exit reason/info, it's probably worth converting all the
KVM_EXIT_INTERNAL_ERROR paths in sgx.c, even though the others don't clobber flags.

2021-08-02 07:20:14

by David Edmondson

Subject: Re: [PATCH v3 3/3] KVM: x86: SGX must obey the KVM_INTERNAL_ERROR_EMULATION protocol

On Friday, 2021-07-30 at 22:17:02 GMT, Sean Christopherson wrote:

> On Thu, Jul 29, 2021, David Edmondson wrote:
>> When passing the failing address and size out to user space, SGX must
>> ensure not to trample on the earlier fields of the emulation_failure
>> sub-union of struct kvm_run.
>>
>> Signed-off-by: David Edmondson <[email protected]>
>> ---
>> arch/x86/kvm/vmx/sgx.c | 8 +++-----
>> 1 file changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
>> index 6693ebdc0770..63fb93163383 100644
>> --- a/arch/x86/kvm/vmx/sgx.c
>> +++ b/arch/x86/kvm/vmx/sgx.c
>> @@ -53,11 +53,9 @@ static int sgx_get_encls_gva(struct kvm_vcpu *vcpu, unsigned long offset,
>> static void sgx_handle_emulation_failure(struct kvm_vcpu *vcpu, u64 addr,
>> unsigned int size)
>> {
>> - vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
>> - vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
>> - vcpu->run->internal.ndata = 2;
>> - vcpu->run->internal.data[0] = addr;
>> - vcpu->run->internal.data[1] = size;
>> + uint64_t data[2] = { addr, size };
>> +
>> + kvm_prepare_emulation_failure_exit(vcpu, false, data, sizeof(data));
>
> Assuming we go with my suggestion to have kvm_prepare_emulation_failure_exit()
> capture the exit reason/info, it's probably worth converting all the
> KVM_EXIT_INTERNAL_ERROR paths in sgx.c, even though the others don't clobber flags.

Okay.