Re: [kvm-unit-tests PATCH v2 5/5] s390x: edat test

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Tue, 23 Feb 2021 15:57:30 +0100
Janosch Frank <frankja@linux.ibm.com> wrote:

> On 2/23/21 3:07 PM, Claudio Imbrenda wrote:
> > Simple EDAT test.
> > 
> > Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> > ---
> >  s390x/Makefile      |   1 +
> >  s390x/edat.c        | 285
> > ++++++++++++++++++++++++++++++++++++++++++++ s390x/unittests.cfg |
> >  3 + 3 files changed, 289 insertions(+)
> >  create mode 100644 s390x/edat.c
> > 
> > diff --git a/s390x/Makefile b/s390x/Makefile
> > index 08d85c9f..fc885150 100644
> > --- a/s390x/Makefile
> > +++ b/s390x/Makefile
> > @@ -20,6 +20,7 @@ tests += $(TEST_DIR)/sclp.elf
> >  tests += $(TEST_DIR)/css.elf
> >  tests += $(TEST_DIR)/uv-guest.elf
> >  tests += $(TEST_DIR)/sie.elf
> > +tests += $(TEST_DIR)/edat.elf
> >  
> >  tests_binary = $(patsubst %.elf,%.bin,$(tests))
> >  ifneq ($(HOST_KEY_DOCUMENT),)
> > diff --git a/s390x/edat.c b/s390x/edat.c
> > new file mode 100644
> > index 00000000..0bd16efc
> > --- /dev/null
> > +++ b/s390x/edat.c
> > @@ -0,0 +1,285 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * EDAT test.
> > + *
> > + * Copyright (c) 2021 IBM Corp
> > + *
> > + * Authors:
> > + *	Claudio Imbrenda <imbrenda@linux.ibm.com>
> > + */
> > +#include <libcflat.h>
> > +#include <vmalloc.h>
> > +#include <asm/facility.h>
> > +#include <asm/interrupt.h>
> > +#include <mmu.h>
> > +#include <asm/pgtable.h>
> > +#include <asm-generic/barrier.h>
> > +
> > +#define PGD_PAGE_SHIFT (REGION1_SHIFT - PAGE_SHIFT)
> > +
> > +#define TEID_ADDR	PAGE_MASK
> > +#define TEID_AI		0x003
> > +#define TEID_M		0x004
> > +#define TEID_A		0x008
> > +#define TEID_FS		0xc00  
> 
> 
> I'm thinking about presenting faults in more detail in the future i.e.
> printing the TEID or at least the important parts of it. I'd guess
> this should go into the library.

will do

> 
> > +
> > +#define LC_SIZE	(2 * PAGE_SIZE)
> > +#define VIRT(x)	((void *)((unsigned long)(x) + (unsigned
> > long)mem)) +
> > +static uint8_t prefix_buf[LC_SIZE]
> > __attribute__((aligned(LC_SIZE))); +static unsigned int tmp[1024]
> > __attribute__((aligned(PAGE_SIZE))); +static void *root, *mem, *m;
> > +static struct lowcore *lc;
> > +volatile unsigned int *p;
> > +
> > +/* Expect a program interrupt, and clear the TEID */
> > +static void expect_dat_fault(void)
> > +{
> > +	expect_pgm_int();
> > +	lc->trans_exc_id = 0;
> > +}
> > +
> > +/*
> > + * Check if a non-access-list protection exception happened for
> > the given
> > + * address, in the primary address space.
> > + */
> > +static bool check_pgm_prot(void *ptr)
> > +{
> > +	unsigned long teid = lc->trans_exc_id;
> > +
> > +	if (lc->pgm_int_code != PGM_INT_CODE_PROTECTION)
> > +		return false;
> > +	/*
> > +	 * if for any reason TEID_M is not present, the rest of
> > the field is
> > +	 * not meaningful, so no point in checking it
> > +	 */
> > +	if (~teid & TEID_M)
> > +		return true;
> > +	return (~teid & TEID_A) &&
> > +		((teid & TEID_ADDR) == ((uint64_t)ptr &
> > PAGE_MASK)) &&
> > +		!(teid & TEID_AI);
> > +}
> > +
> > +static void test_dat(void)
> > +{
> > +	report_prefix_push("edat off");
> > +	/* disable EDAT */
> > +	ctl_clear_bit(0, 23);  
> 
> It's about time we properly define CTL0 bits.

will do

> > +
> > +	/* Check some basics */
> > +	p[0] = 42;
> > +	report(p[0] == 42, "pte, r/w");
> > +	p[0] = 0;
> > +
> > +	/* Write protect the page and try to write, expect a fault
> > */
> > +	protect_page(m, PAGE_ENTRY_P);
> > +	expect_dat_fault();
> > +	p[0] = 42;
> > +	unprotect_page(m, PAGE_ENTRY_P);
> > +	report(!p[0] && check_pgm_prot(m), "pte, ro");
> > +
> > +	/*
> > +	 * The FC bit (for large pages) should be ignored because
> > EDAT is
> > +	 * off. We set a value and then we try to read it back
> > again after
> > +	 * setting the FC bit. This way we can check if large
> > pages were
> > +	 * erroneously enabled despite EDAT being off.
> > +	 */
> > +	p[0] = 42;
> > +	protect_dat_entry(m, SEGMENT_ENTRY_FC, 4);
> > +	report(p[0] == 42, "pmd, fc=1, r/w");
> > +	unprotect_dat_entry(m, SEGMENT_ENTRY_FC, 4);
> > +	p[0] = 0;
> > +
> > +	/*
> > +	 * Segment protection should work even with EDAT off, try
> > to write
> > +	 * anyway and expect a fault
> > +	 */
> > +	protect_dat_entry(m, SEGMENT_ENTRY_P, 4);
> > +	expect_dat_fault();
> > +	p[0] = 42;
> > +	report(!p[0] && check_pgm_prot(m), "pmd, ro");
> > +	unprotect_dat_entry(m, SEGMENT_ENTRY_P, 4);
> > +
> > +	/* The FC bit should be ignored because EDAT is off, like
> > above */
> > +	p[0] = 42;
> > +	protect_dat_entry(m, REGION3_ENTRY_FC, 3);
> > +	report(p[0] == 42, "pud, fc=1, r/w");
> > +	unprotect_dat_entry(m, REGION3_ENTRY_FC, 3);
> > +	p[0] = 0;
> > +
> > +	/*
> > +	 * Region1/2/3 protection should not work, because EDAT is
> > off.
> > +	 * Protect the various region1/2/3 entries and write,
> > expect the
> > +	 * write to be successful.
> > +	 */
> > +	protect_dat_entry(m, REGION_ENTRY_P, 3);
> > +	p[0] = 42;
> > +	report(p[0] == 42, "pud, ro");
> > +	unprotect_dat_entry(m, REGION_ENTRY_P, 3);
> > +	p[0] = 0;
> > +
> > +	protect_dat_entry(m, REGION_ENTRY_P, 2);
> > +	p[0] = 42;
> > +	report(p[0] == 42, "p4d, ro");
> > +	unprotect_dat_entry(m, REGION_ENTRY_P, 2);
> > +	p[0] = 0;
> > +
> > +	protect_dat_entry(m, REGION_ENTRY_P, 1);
> > +	p[0] = 42;
> > +	report(p[0] == 42, "pgd, ro");
> > +	unprotect_dat_entry(m, REGION_ENTRY_P, 1);
> > +	p[0] = 0;
> > +
> > +	report_prefix_pop();
> > +}
> > +
> > +static void test_edat1(void)
> > +{
> > +	report_prefix_push("edat1");
> > +	/* Enable EDAT */
> > +	ctl_set_bit(0, 23);
> > +	p[0] = 0;
> > +
> > +	/*
> > +	 * Segment protection should work normally, try to write
> > and expect
> > +	 * a fault.
> > +	 */
> > +	expect_dat_fault();
> > +	protect_dat_entry(m, SEGMENT_ENTRY_P, 4);
> > +	p[0] = 42;
> > +	report(!p[0] && check_pgm_prot(m), "pmd, ro");
> > +	unprotect_dat_entry(m, SEGMENT_ENTRY_P, 4);
> > +
> > +	/*
> > +	 * Region1/2/3 protection should work now, because EDAT is
> > on. Try
> > +	 * to write anyway and expect a fault.
> > +	 */
> > +	expect_dat_fault();
> > +	protect_dat_entry(m, REGION_ENTRY_P, 3);
> > +	p[0] = 42;
> > +	report(!p[0] && check_pgm_prot(m), "pud, ro");
> > +	unprotect_dat_entry(m, REGION_ENTRY_P, 3);
> > +
> > +	expect_dat_fault();
> > +	protect_dat_entry(m, REGION_ENTRY_P, 2);
> > +	p[0] = 42;
> > +	report(!p[0] && check_pgm_prot(m), "p4d, ro");
> > +	unprotect_dat_entry(m, REGION_ENTRY_P, 2);
> > +
> > +	expect_dat_fault();
> > +	protect_dat_entry(m, REGION_ENTRY_P, 1);
> > +	p[0] = 42;
> > +	report(!p[0] && check_pgm_prot(m), "pgd, ro");
> > +	unprotect_dat_entry(m, REGION_ENTRY_P, 1);
> > +
> > +	/* Large pages should work */
> > +	p[0] = 42;
> > +	install_large_page(root, 0, mem);
> > +	report(p[0] == 42, "pmd, large");
> > +
> > +	/*
> > +	 * Prefixing should not work with large pages. Since the
> > lower
> > +	 * addresses are mapped with small pages, which are
> > subject to
> > +	 * prefixing, and the pages mapped with large pages are
> > not subject
> > +	 * to prefixing, this is the resulting scenario:
> > +	 *
> > +	 * virtual 0 = real 0 -> absolute prefix_buf
> > +	 * virtual prefix_buf = real prefix_buf -> absolute 0
> > +	 * VIRT(0) -> absolute 0
> > +	 * VIRT(prefix_buf) -> absolute prefix_buf
> > +	 *
> > +	 * The testcase checks if the memory at virtual 0 has the
> > same
> > +	 * content as the memory at VIRT(prefix_buf) and the
> > memory at
> > +	 * VIRT(0) has the same content as the memory at virtual
> > prefix_buf.
> > +	 * If prefixing is erroneously applied for large pages,
> > the testcase
> > +	 * will therefore fail.
> > +	 */
> > +	report(!memcmp(0, VIRT(prefix_buf), LC_SIZE) &&
> > +		!memcmp(prefix_buf, VIRT(0), LC_SIZE),
> > +		"pmd, large, prefixing");
> > +
> > +	report_prefix_pop();
> > +}
> > +
> > +static void test_edat2(void)
> > +{
> > +	report_prefix_push("edat2");
> > +	p[0] = 42;
> > +
> > +	/* Huge pages should work */
> > +	install_huge_page(root, 0, mem);
> > +	report(p[0] == 42, "pud, huge");
> > +
> > +	/* Prefixing should not work with huge pages, just like
> > large pages */
> > +	report(!memcmp(0, VIRT(prefix_buf), LC_SIZE) &&
> > +		!memcmp(prefix_buf, VIRT(0), LC_SIZE),
> > +		"pmd, large, prefixing");
> > +
> > +	report_prefix_pop();
> > +}
> > +
> > +static unsigned int setup(void)
> > +{
> > +	bool has_edat1 = test_facility(8);
> > +	bool has_edat2 = test_facility(78);
> > +	unsigned long pa, va;
> > +
> > +	if (has_edat2 && !has_edat1)
> > +		report_abort("EDAT2 available, but EDAT1 not
> > available"); +
> > +	/* Setup DAT 1:1 mapping and memory management */
> > +	setup_vm();
> > +	root = (void *)(stctg(1) & PAGE_MASK);
> > +
> > +	/*
> > +	 * Get a pgd worth of virtual memory, so we can test
> > things later
> > +	 * without interfering with the test code or the interrupt
> > handler
> > +	 */
> > +	mem = alloc_vpages_aligned(BIT_ULL(PGD_PAGE_SHIFT),
> > PGD_PAGE_SHIFT);
> > +	assert(mem);
> > +	va = (unsigned long)mem;
> > +
> > +	/* Map the first 1GB of real memory */
> > +	for (pa = 0; pa < SZ_1G; pa += PAGE_SIZE, va += PAGE_SIZE)
> > +		install_page(root, pa, (void *)va);
> > +
> > +	/*
> > +	 * Move the lowcore to a known non-zero location. This is
> > needed
> > +	 * later to check whether prefixing is working with large
> > pages.
> > +	 */
> > +	assert((unsigned long)&prefix_buf < SZ_2G);
> > +	memcpy(prefix_buf, 0, LC_SIZE);
> > +	set_prefix((uint32_t)(uintptr_t)prefix_buf);
> > +	/* Clear the old copy */
> > +	memset(prefix_buf, 0, LC_SIZE);
> > +
> > +	/* m will point to tmp through the new virtual mapping */
> > +	m = VIRT(&tmp);
> > +	/* p is the same as m but volatile */
> > +	p = (volatile unsigned int *)m;
> > +
> > +	return has_edat1 + has_edat2;
> > +}
> > +
> > +int main(void)
> > +{
> > +	unsigned int edat;
> > +
> > +	report_prefix_push("edat");
> > +	edat = setup();
> > +
> > +	test_dat();
> > +
> > +	if (edat)
> > +		test_edat1();
> > +	else
> > +		report_skip("EDAT not available");
> > +
> > +	if (edat >= 2)
> > +		test_edat2();
> > +	else
> > +		report_skip("EDAT2 not available");
> > +
> > +	report_prefix_pop();
> > +	return report_summary();
> > +}
> > diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
> > index 2298be6c..8da4a0a3 100644
> > --- a/s390x/unittests.cfg
> > +++ b/s390x/unittests.cfg
> > @@ -99,3 +99,6 @@ file = uv-guest.elf
> >  
> >  [sie]
> >  file = sie.elf
> > +
> > +[edat]
> > +file = edat.elf
> >   
>