iommu/amd: Clean up RMP entries for IOMMU pages during SNP shutdown

Add a new IOMMU API interface amd_iommu_snp_disable() to transition
IOMMU pages to Hypervisor state from Reclaim state after SNP_SHUTDOWN_EX
command. Invoke this API from the CCP driver after SNP_SHUTDOWN_EX
command.

Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-20-michael.roth@amd.com

1 files changed, 79 insertions, 0 deletions

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 3a4eeb26d515..88bb08ae39b2 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -30,6 +30,7 @@
 #include <asm/io_apic.h>
 #include <asm/irq_remapping.h>
 #include <asm/set_memory.h>
+#include <asm/sev.h>
 
 #include <linux/crash_dump.h>
 
@@ -3797,3 +3798,81 @@ int amd_iommu_pc_set_reg(struct amd_iommu *iommu, u8 bank, u8 cntr, u8 fxn, u64
 
 	return iommu_pc_get_set_reg(iommu, bank, cntr, fxn, value, true);
 }
+
+#ifdef CONFIG_KVM_AMD_SEV
+static int iommu_page_make_shared(void *page)
+{
+	unsigned long paddr, pfn;
+
+	paddr = iommu_virt_to_phys(page);
+	/* Cbit maybe set in the paddr */
+	pfn = __sme_clr(paddr) >> PAGE_SHIFT;
+
+	if (!(pfn % PTRS_PER_PMD)) {
+		int ret, level;
+		bool assigned;
+
+		ret = snp_lookup_rmpentry(pfn, &assigned, &level);
+		if (ret)
+			pr_warn("IOMMU PFN %lx RMP lookup failed, ret %d\n",
+				pfn, ret);
+
+		if (!assigned)
+			pr_warn("IOMMU PFN %lx not assigned in RMP table\n",
+				pfn);
+
+		if (level > PG_LEVEL_4K) {
+			ret = psmash(pfn);
+			if (ret) {
+				pr_warn("IOMMU PFN %lx had a huge RMP entry, but attempted psmash failed, ret: %d, level: %d\n",
+					pfn, ret, level);
+			}
+		}
+	}
+
+	return rmp_make_shared(pfn, PG_LEVEL_4K);
+}
+
+static int iommu_make_shared(void *va, size_t size)
+{
+	void *page;
+	int ret;
+
+	if (!va)
+		return 0;
+
+	for (page = va; page < (va + size); page += PAGE_SIZE) {
+		ret = iommu_page_make_shared(page);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int amd_iommu_snp_disable(void)
+{
+	struct amd_iommu *iommu;
+	int ret;
+
+	if (!amd_iommu_snp_en)
+		return 0;
+
+	for_each_iommu(iommu) {
+		ret = iommu_make_shared(iommu->evt_buf, EVT_BUFFER_SIZE);
+		if (ret)
+			return ret;
+
+		ret = iommu_make_shared(iommu->ppr_log, PPR_LOG_SIZE);
+		if (ret)
+			return ret;
+
+		ret = iommu_make_shared((void *)iommu->cmd_sem, PAGE_SIZE);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(amd_iommu_snp_disable);
+#endif