On 08.08.2025 22:23, Andrew Cooper wrote:
> @@ -42,17 +46,76 @@ struct cpu_user_regs
> */
>
> union { uint64_t rip; uint32_t eip; uint16_t ip; };
> - uint16_t cs, _pad0[1];
> - uint8_t saved_upcall_mask; /* PV (v)rflags.IF == !saved_upcall_mask */
> - uint8_t _pad1[3];
> + union {
> + struct {
> + uint16_t cs;
> + unsigned long :16;
> + uint8_t saved_upcall_mask; /* PV (v)rflags.IF ==
> !saved_upcall_mask */
Would this better be reproduced ...
> + };
> + unsigned long csx;
> + struct {
> + /*
> + * Bits 0 thru 31 control ERET{U,S} behaviour, and is state of
> the
> + * interrupted context.
> + */
> + uint16_t cs;
> + unsigned int sl:2; /* Stack Level */
> + bool wfe:1; /* Wait-for-ENDBRANCH state */
... here as well, just like you reproduce "cs"?
> + } fred_cs;
> + };
> union { uint64_t rflags; uint32_t eflags; uint16_t flags; };
> union { uint64_t rsp; uint32_t esp; uint16_t sp; uint8_t spl; };
> - uint16_t ss, _pad2[3];
> + union {
> + uint16_t ss;
> + unsigned long ssx;
What use do you foresee for this and "csx"?
> + struct {
> + /*
> + * Bits 0 thru 31 control ERET{U,S} behaviour, and is state about
> + * the event which occured.
> + */
> + uint16_t ss;
> + bool sti:1; /* Was blocked-by-STI, and not
> cancelled */
> + bool swint:1; /* Was a SYSCALL/SYSENTER/INT $N */
> + bool nmi:1; /* Was an NMI. */
> + unsigned long :13;
> +
> + /*
> + * Bits 32 thru 63 are ignored by ERET{U,S} and are informative
> + * only.
> + */
> + uint8_t vector;
> + unsigned long :8;
> + unsigned int type:4; /* X86_ET_* */
> + unsigned long :4;
> + bool enclave:1; /* Event taken in SGX mode */
> + bool lm:1; /* Was in Long Mode */
The bit indicates 64-bit mode aiui, not long mode (without which FRED isn't even
available).
> --- a/xen/arch/x86/include/asm/current.h
> +++ b/xen/arch/x86/include/asm/current.h
> @@ -38,6 +38,8 @@ struct vcpu;
>
> struct cpu_info {
> struct cpu_user_regs guest_cpu_user_regs;
> + struct fred_info _fred; /* Only used when FRED is active. */
Any particular need for the leading underscore?
Jan
