Commit f366a8da authored by Ashish Kalra's avatar Ashish Kalra Committed by Borislav Petkov (AMD)
Browse files

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: default avatarAshish Kalra <ashish.kalra@amd.com>
Signed-off-by: default avatarMichael Roth <michael.roth@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-20-michael.roth@amd.com
parent a867ad6b

drivers/crypto/ccp/sev-dev.c

+20 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <linux/fs.h>

#include <linux/fs_struct.h>

#include <linux/psp.h>

#include <linux/amd-iommu.h>



#include <asm/smp.h>

#include <asm/cacheflush.h>
@@ -1655,6 +1656,25 @@ static int __sev_snp_shutdown_locked(int *error) 
		return ret;

	}



	/*

	 * SNP_SHUTDOWN_EX with IOMMU_SNP_SHUTDOWN set to 1 disables SNP

	 * enforcement by the IOMMU and also transitions all pages

	 * associated with the IOMMU to the Reclaim state.

	 * Firmware was transitioning the IOMMU pages to Hypervisor state

	 * before version 1.53. But, accounting for the number of assigned

	 * 4kB pages in a 2M page was done incorrectly by not transitioning

	 * to the Reclaim state. This resulted in RMP #PF when later accessing

	 * the 2M page containing those pages during kexec boot. Hence, the

	 * firmware now transitions these pages to Reclaim state and hypervisor

	 * needs to transition these pages to shared state. SNP Firmware

	 * version 1.53 and above are needed for kexec boot.

	 */

	ret = amd_iommu_snp_disable();

	if (ret) {

		dev_err(sev->dev, "SNP IOMMU shutdown failed\n");

		return ret;

	}



	sev->snp_initialized = false;

	dev_dbg(sev->dev, "SEV-SNP firmware shutdown\n");

drivers/iommu/amd/init.c

+79 −0
Original line number Diff line number Diff line
@@ -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

include/linux/amd-iommu.h

+6 −0
Original line number Diff line number Diff line
@@ -85,4 +85,10 @@ int amd_iommu_pc_get_reg(struct amd_iommu *iommu, u8 bank, u8 cntr, u8 fxn, 
		u64 *value);

struct amd_iommu *get_amd_iommu(unsigned int idx);



#ifdef CONFIG_KVM_AMD_SEV

int amd_iommu_snp_disable(void);

#else

static inline int amd_iommu_snp_disable(void) { return 0; }

#endif



#endif /* _ASM_X86_AMD_IOMMU_H */