Re: [PATCH Part2 v6 07/49] x86/sev: Invalid pages from direct map when adding it to RMP table
From: Borislav Petkov <bp@alien8.de>
Date: 2022-07-27 17:57:50
Also in:
kvm, linux-crypto, linux-mm, lkml
On Mon, Jun 20, 2022 at 11:03:07PM +0000, Ashish Kalra wrote:
Subject: x86/sev: Invalid pages from direct map when adding it to RMP table
"...: Invalidate pages from the direct map when adding them to the RMP table"
+static int restore_direct_map(u64 pfn, int npages)
+{
+ int i, ret = 0;
+
+ for (i = 0; i < npages; i++) {
+ ret = set_direct_map_default_noflush(pfn_to_page(pfn + i));set_memory_p() ?
+ if (ret) + goto cleanup; + } + +cleanup: + WARN(ret > 0, "Failed to restore direct map for pfn 0x%llx\n", pfn + i);
Warn for each pfn?! That'll flood dmesg mightily.
+ return ret;
+}
+
+static int invalid_direct_map(unsigned long pfn, int npages)
+{
+ int i, ret = 0;
+
+ for (i = 0; i < npages; i++) {
+ ret = set_direct_map_invalid_noflush(pfn_to_page(pfn + i));As above, set_memory_np() doesn't work here instead of looping over each page?
quoted hunk ↗ jump to hunk
@@ -2462,11 +2494,38 @@ static int rmpupdate(u64 pfn, struct rmpupdate *val) if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) return -ENXIO; + level = RMP_TO_X86_PG_LEVEL(val->pagesize); + npages = page_level_size(level) / PAGE_SIZE; + + /* + * If page is getting assigned in the RMP table then unmap it from the + * direct map. + */ + if (val->assigned) { + if (invalid_direct_map(pfn, npages)) { + pr_err("Failed to unmap pfn 0x%llx pages %d from direct_map\n",
"Failed to unmap %d pages at pfn 0x... from the direct map\n"
+ pfn, npages);
+ return -EFAULT;
+ }
+ }
+
/* Binutils version 2.36 supports the RMPUPDATE mnemonic. */
asm volatile(".byte 0xF2, 0x0F, 0x01, 0xFE"
: "=a"(ret)
: "a"(paddr), "c"((unsigned long)val)
: "memory", "cc");
+
+ /*
+ * Restore the direct map after the page is removed from the RMP table.
+ */
+ if (!ret && !val->assigned) {
+ if (restore_direct_map(pfn, npages)) {
+ pr_err("Failed to map pfn 0x%llx pages %d in direct_map\n",
"Failed to map %d pages at pfn 0x... into the direct map\n"
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette