On 5/20/21 12:52 PM, Borislav Petkov wrote:

On Fri, Apr 30, 2021 at 07:16:07AM -0500, Brijesh Singh wrote:

quoted

@@ -278,12 +279,28 @@ static int set_clr_page_flags(struct x86_mapping_info *info,
 	if ((set | clr) & _PAGE_ENC)
 		clflush_page(address);
 
+	/*
+	 * If the encryption attribute is being cleared, then change the page state to
+	 * shared in the RMP entry. Change of the page state must be done before the
+	 * PTE updates.
+	 */
+	if (clr & _PAGE_ENC)
+		snp_set_page_shared(pte_pfn(*ptep) << PAGE_SHIFT);

From the last review:

The statement above already looks at clr - just merge the two together.

Maybe I am missing something, the statement above was executed for
either set or clr but the page shared need to happen only for clr. So,
from code readability point I kept it outside of that if().

Otherwise we may have to do something like.

...

if ((set | clr) & _PAGE_EN) {

   if (clr)

    snp_set_page_shared(pte_pfn(*ptep) << PAGE_SHIFT);

  }

I am okay with above is the preferred approach.

quoted

@@ -136,6 +137,55 @@ static inline bool sev_snp_enabled(void)
 	return sev_status_val & MSR_AMD64_SEV_SNP_ENABLED ? true : false;
 }
 
+static void snp_page_state_change(unsigned long paddr, int op)

From the last review:

no need for too many prefixes on static functions - just call this one
__change_page_state() or so, so that the below one can be called...

I guess I still kept the "snp" prefix because vmgexit was named that
way. Based on your feedback, I am droping the "SNP" prefix from the
VMGEXIT and will update it as well.

quoted

+{
+	u64 val;
+
+	if (!sev_snp_enabled())
+		return;
+
+	/*
+	 * If the page is getting changed from private to shard then invalidate the page

							shared

And you can write this a lot shorter

	* If private -> shared, ...

quoted

+	 * before requesting the state change in the RMP table.
+	 */
+	if ((op == SNP_PAGE_STATE_SHARED) && pvalidate(paddr, RMP_PG_SIZE_4K, 0))
+		goto e_pvalidate;
+
+	/* Issue VMGEXIT to change the page state in RMP table. */
+	sev_es_wr_ghcb_msr(GHCB_MSR_PSC_REQ_GFN(paddr >> PAGE_SHIFT, op));
+	VMGEXIT();
+
+	/* Read the response of the VMGEXIT. */
+	val = sev_es_rd_ghcb_msr();
+	if ((GHCB_RESP_CODE(val) != GHCB_MSR_PSC_RESP) || GHCB_MSR_PSC_RESP_VAL(val))
+		goto e_psc;

That label is used only once - just do the termination here directly and
remove it.

Noted.

Thx.