On Tue, 2023-11-07 at 06:55 -0800, isaku.yamahata@xxxxxxxxx wrote:
> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
>
> Some SEAMCALL may return TDX_RND_NO_ENTROPY error when the entropy is
> lacking. Retry SEAMCALL on the error following rdrand_long() to retry
> RDRAND_RETRY_LOOPS times.
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx/tdx_errno.h | 1 +
> arch/x86/kvm/vmx/tdx_ops.h | 40 +++++++++++++++++++++---------------
> 2 files changed, 24 insertions(+), 17 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/tdx_errno.h b/arch/x86/kvm/vmx/tdx_errno.h
> index 7f96696b8e7c..bb093e292fef 100644
> --- a/arch/x86/kvm/vmx/tdx_errno.h
> +++ b/arch/x86/kvm/vmx/tdx_errno.h
> @@ -14,6 +14,7 @@
> #define TDX_OPERAND_INVALID 0xC000010000000000ULL
> #define TDX_OPERAND_BUSY 0x8000020000000000ULL
> #define TDX_PREVIOUS_TLB_EPOCH_BUSY 0x8000020100000000ULL
> +#define TDX_RND_NO_ENTROPY 0x8000020300000000ULL
> #define TDX_VCPU_NOT_ASSOCIATED 0x8000070200000000ULL
> #define TDX_KEY_GENERATION_FAILED 0x8000080000000000ULL
> #define TDX_KEY_STATE_INCORRECT 0xC000081100000000ULL
> diff --git a/arch/x86/kvm/vmx/tdx_ops.h b/arch/x86/kvm/vmx/tdx_ops.h
> index 12fd6b8d49e0..a55977626ae3 100644
> --- a/arch/x86/kvm/vmx/tdx_ops.h
> +++ b/arch/x86/kvm/vmx/tdx_ops.h
> @@ -6,6 +6,7 @@
>
> #include <linux/compiler.h>
>
> +#include <asm/archrandom.h>
> #include <asm/cacheflush.h>
> #include <asm/asm.h>
> #include <asm/kvm_host.h>
> @@ -17,25 +18,30 @@
> static inline u64 tdx_seamcall(u64 op, u64 rcx, u64 rdx, u64 r8, u64 r9,
> struct tdx_module_args *out)
> {
> + int retry;
> u64 ret;
>
> - if (out) {
> - *out = (struct tdx_module_args) {
> - .rcx = rcx,
> - .rdx = rdx,
> - .r8 = r8,
> - .r9 = r9,
> - };
> - ret = __seamcall_ret(op, out);
> - } else {
> - struct tdx_module_args args = {
> - .rcx = rcx,
> - .rdx = rdx,
> - .r8 = r8,
> - .r9 = r9,
> - };
> - ret = __seamcall(op, &args);
> - }
> + /* Mimic the existing rdrand_long() to retry RDRAND_RETRY_LOOPS times. */
> + retry = RDRAND_RETRY_LOOPS;
> + do {
> + if (out) {
> + *out = (struct tdx_module_args) {
> + .rcx = rcx,
> + .rdx = rdx,
> + .r8 = r8,
> + .r9 = r9,
> + };
> + ret = __seamcall_ret(op, out);
> + } else {
> + struct tdx_module_args args = {
> + .rcx = rcx,
> + .rdx = rdx,
> + .r8 = r8,
> + .r9 = r9,
> + };
> + ret = __seamcall(op, &args);
> + }
> + } while (unlikely(ret == TDX_RND_NO_ENTROPY) && --retry);
> if (unlikely(ret == TDX_SEAMCALL_UD)) {
> /*
> * SEAMCALLs fail with TDX_SEAMCALL_UD returned when VMX is off.
Why we cannot use seamcall*() variants directly which already handles running
out of entropy error?
