Commit 7e20d344 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86-urgent-2023-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull misc x86 fixes from Ingo Molnar:

 - Fix SEV-SNP guest crashes that may happen on NMIs

 - Fix a potential SEV platform memory setup overflow

* tag 'x86-urgent-2023-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/sev: Change npages to unsigned long in snp_accept_memory()
  x86/sev: Use the GHCB protocol when available for SNP CPUID requests
parents b9ddbb0c 62d5e970

arch/x86/kernel/sev-shared.c

+55 −14
Original line number Diff line number Diff line
@@ -256,7 +256,7 @@ static int __sev_cpuid_hv(u32 fn, int reg_idx, u32 *reg) 
	return 0;

}



static int sev_cpuid_hv(struct cpuid_leaf *leaf)

static int __sev_cpuid_hv_msr(struct cpuid_leaf *leaf)

{

	int ret;
@@ -279,6 +279,45 @@ static int sev_cpuid_hv(struct cpuid_leaf *leaf) 
	return ret;

}



static int __sev_cpuid_hv_ghcb(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)

{

	u32 cr4 = native_read_cr4();

	int ret;



	ghcb_set_rax(ghcb, leaf->fn);

	ghcb_set_rcx(ghcb, leaf->subfn);



	if (cr4 & X86_CR4_OSXSAVE)

		/* Safe to read xcr0 */

		ghcb_set_xcr0(ghcb, xgetbv(XCR_XFEATURE_ENABLED_MASK));

	else

		/* xgetbv will cause #UD - use reset value for xcr0 */

		ghcb_set_xcr0(ghcb, 1);



	ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0);

	if (ret != ES_OK)

		return ret;



	if (!(ghcb_rax_is_valid(ghcb) &&

	      ghcb_rbx_is_valid(ghcb) &&

	      ghcb_rcx_is_valid(ghcb) &&

	      ghcb_rdx_is_valid(ghcb)))

		return ES_VMM_ERROR;



	leaf->eax = ghcb->save.rax;

	leaf->ebx = ghcb->save.rbx;

	leaf->ecx = ghcb->save.rcx;

	leaf->edx = ghcb->save.rdx;



	return ES_OK;

}



static int sev_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)

{

	return ghcb ? __sev_cpuid_hv_ghcb(ghcb, ctxt, leaf)

		    : __sev_cpuid_hv_msr(leaf);

}



/*

 * This may be called early while still running on the initial identity

 * mapping. Use RIP-relative addressing to obtain the correct address
@@ -388,19 +427,20 @@ snp_cpuid_get_validated_func(struct cpuid_leaf *leaf) 
	return false;

}



static void snp_cpuid_hv(struct cpuid_leaf *leaf)

static void snp_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)

{

	if (sev_cpuid_hv(leaf))

	if (sev_cpuid_hv(ghcb, ctxt, leaf))

		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID_HV);

}



static int snp_cpuid_postprocess(struct cpuid_leaf *leaf)

static int snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt,

				 struct cpuid_leaf *leaf)

{

	struct cpuid_leaf leaf_hv = *leaf;



	switch (leaf->fn) {

	case 0x1:

		snp_cpuid_hv(&leaf_hv);

		snp_cpuid_hv(ghcb, ctxt, &leaf_hv);



		/* initial APIC ID */

		leaf->ebx = (leaf_hv.ebx & GENMASK(31, 24)) | (leaf->ebx & GENMASK(23, 0));
@@ -419,7 +459,7 @@ static int snp_cpuid_postprocess(struct cpuid_leaf *leaf) 
		break;

	case 0xB:

		leaf_hv.subfn = 0;

		snp_cpuid_hv(&leaf_hv);

		snp_cpuid_hv(ghcb, ctxt, &leaf_hv);



		/* extended APIC ID */

		leaf->edx = leaf_hv.edx;
@@ -467,7 +507,7 @@ static int snp_cpuid_postprocess(struct cpuid_leaf *leaf) 
		}

		break;

	case 0x8000001E:

		snp_cpuid_hv(&leaf_hv);

		snp_cpuid_hv(ghcb, ctxt, &leaf_hv);



		/* extended APIC ID */

		leaf->eax = leaf_hv.eax;
@@ -488,7 +528,7 @@ static int snp_cpuid_postprocess(struct cpuid_leaf *leaf) 
 * Returns -EOPNOTSUPP if feature not enabled. Any other non-zero return value

 * should be treated as fatal by caller.

 */

static int snp_cpuid(struct cpuid_leaf *leaf)

static int snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)

{

	const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
@@ -522,7 +562,7 @@ static int snp_cpuid(struct cpuid_leaf *leaf) 
			return 0;

	}



	return snp_cpuid_postprocess(leaf);

	return snp_cpuid_postprocess(ghcb, ctxt, leaf);

}



/*
@@ -544,14 +584,14 @@ void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code) 
	leaf.fn = fn;

	leaf.subfn = subfn;



	ret = snp_cpuid(&leaf);

	ret = snp_cpuid(NULL, NULL, &leaf);

	if (!ret)

		goto cpuid_done;



	if (ret != -EOPNOTSUPP)

		goto fail;



	if (sev_cpuid_hv(&leaf))

	if (__sev_cpuid_hv_msr(&leaf))

		goto fail;



cpuid_done:
@@ -848,14 +888,15 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) 
	return ret;

}



static int vc_handle_cpuid_snp(struct pt_regs *regs)

static int vc_handle_cpuid_snp(struct ghcb *ghcb, struct es_em_ctxt *ctxt)

{

	struct pt_regs *regs = ctxt->regs;

	struct cpuid_leaf leaf;

	int ret;



	leaf.fn = regs->ax;

	leaf.subfn = regs->cx;

	ret = snp_cpuid(&leaf);

	ret = snp_cpuid(ghcb, ctxt, &leaf);

	if (!ret) {

		regs->ax = leaf.eax;

		regs->bx = leaf.ebx;
@@ -874,7 +915,7 @@ static enum es_result vc_handle_cpuid(struct ghcb *ghcb, 
	enum es_result ret;

	int snp_cpuid_ret;



	snp_cpuid_ret = vc_handle_cpuid_snp(regs);

	snp_cpuid_ret = vc_handle_cpuid_snp(ghcb, ctxt);

	if (!snp_cpuid_ret)

		return ES_OK;

	if (snp_cpuid_ret != -EOPNOTSUPP)

arch/x86/kernel/sev.c

+1 −2
Original line number Diff line number Diff line
@@ -868,8 +868,7 @@ void snp_set_memory_private(unsigned long vaddr, unsigned long npages) 


void snp_accept_memory(phys_addr_t start, phys_addr_t end)

{

	unsigned long vaddr;

	unsigned int npages;

	unsigned long vaddr, npages;



	if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))

		return;