Re: [PATCH Part1 RFC v2 10/20] x86/sev: Add a helper for the PVALIDATE instruction
From: Borislav Petkov <bp@alien8.de>
Date: 2021-05-20 17:32:56
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On Fri, Apr 30, 2021 at 08:05:36AM -0500, Brijesh Singh wrote:
While generating the patches for part1, I accidentally picked the wrong version of this patch.
Adding the right one...
quoted hunk ↗ jump to hunk
Author: Brijesh Singh [off-list ref] Date: Thu Apr 29 16:45:36 2021 -0500 x86/sev: Add a helper for the PVALIDATE instruction An SNP-active guest uses the PVALIDATE instruction to validate or rescind the validation of a guest page’s RMP entry. Upon completion, a return code is stored in EAX and rFLAGS bits are set based on the return code. If the instruction completed successfully, the CF indicates if the content of the RMP were changed or not. See AMD APM Volume 3 for additional details. Signed-off-by: Brijesh Singh [off-list ref]diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 134a7c9d91b6..be67d9c70267 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h@@ -59,6 +59,16 @@ extern void vc_no_ghcb(void); extern void vc_boot_ghcb(void); extern bool handle_vc_boot_ghcb(struct pt_regs *regs); +/* Return code of pvalidate */ +#define PVALIDATE_SUCCESS 0 +#define PVALIDATE_FAIL_INPUT 1 +#define PVALIDATE_FAIL_SIZEMISMATCH 6
Those are unused. Remove them pls.
+#define PVALIDATE_FAIL_NOUPDATE 255 /* Software defined (when rFlags.CF = 1) */
Put the comment above the define pls.
+ +/* RMP page size */ +#define RMP_PG_SIZE_2M 1 +#define RMP_PG_SIZE_4K 0
Add those when you need them - I see [PATCH Part2 RFC v2 06/37] x86/sev: Add RMP entry lookup helpers is moving them to some generic header. No need to add them to this patch here.
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#ifdef CONFIG_AMD_MEM_ENCRYPT extern struct static_key_false sev_es_enable_key; extern void __sev_es_ist_enter(struct pt_regs *regs);@@ -81,12 +91,29 @@ static __always_inline void sev_es_nmi_complete(void) __sev_es_nmi_complete(); } extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd); +static inline int pvalidate(unsigned long vaddr, bool rmp_psize, bool validate) +{ + bool no_rmpupdate; + int rc;
Adding this for the mail archives when we find this mail again in the
future so that I don't have to do binutils git archeology again:
Enablement for the "pvalidate" mnemonic is in binutils commit
646cc3e0109e ("Add AMD znver3 processor support"). :-)
Please put over the opcode bytes line:
/* "pvalidate" mnemonic support in binutils 2.36 and newer */
+
+ asm volatile(".byte 0xF2, 0x0F, 0x01, 0xFF\n\t"
+ CC_SET(c)
+ : CC_OUT(c) (no_rmpupdate), "=a"(rc)
+ : "a"(vaddr), "c"(rmp_psize), "d"(validate)
+ : "memory", "cc");
+
+ if (no_rmpupdate)
+ return PVALIDATE_FAIL_NOUPDATE;
+
+ return rc;
+}
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette