Re: [PATCH v10 20/38] x86, mpparse: Use memremap to map the mpf and mpc data

[Tom Lendacky <thomas.lendacky@xxxxxxx>]

On 11/3/2017 10:12 AM, Tomeu Vizoso wrote:
> On 17 July 2017 at 23:10, Tom Lendacky <thomas.lendacky@xxxxxxx> wrote:
> > The SMP MP-table is built by UEFI and placed in memory in a decrypted
> > state. These tables are accessed using a mix of early_memremap(),
> > early_memunmap(), phys_to_virt() and virt_to_phys(). Change all accesses
> > to use early_memremap()/early_memunmap(). This allows for proper setting
> > of the encryption mask so that the data can be successfully accessed when
> > SME is active.
> >
> > Reviewed-by: Borislav Petkov <bp@xxxxxxx>
> > Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> > ---
> >   arch/x86/kernel/mpparse.c | 98 +++++++++++++++++++++++++++++++++--------------
> >   1 file changed, 70 insertions(+), 28 deletions(-)
>
> Hi there,
>
> today I played a bit with crosvm [0] and noticed that 4.14-rc7 doesn't
> boot. git-bisect pointed to this patch, and reverting it indeed gets
> things working again.
>
> Anybody has an idea of why this could be?

If you send me your kernel config I'll see if I can reproduce the issue
and debug it.

Thanks,
Tom

> Thanks,
>
> Tomeu
>
> [0] https://chromium.googlesource.com/chromiumos/platform/crosvm
>
> > diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c
> > index fd37f39..5cbb317 100644
> > --- a/arch/x86/kernel/mpparse.c
> > +++ b/arch/x86/kernel/mpparse.c
> > @@ -429,7 +429,7 @@ static inline void __init construct_default_ISA_mptable(int mpc_default_type)
> >          }
> >   }
> >
> > -static struct mpf_intel *mpf_found;
> > +static unsigned long mpf_base;
> >
> >   static unsigned long __init get_mpc_size(unsigned long physptr)
> >   {
> > @@ -451,6 +451,7 @@ static int __init check_physptr(struct mpf_intel *mpf, unsigned int early)
> >
> >          size = get_mpc_size(mpf->physptr);
> >          mpc = early_memremap(mpf->physptr, size);
> > +
> >          /*
> >           * Read the physical hardware table.  Anything here will
> >           * override the defaults.
> > @@ -497,12 +498,12 @@ static int __init check_physptr(struct mpf_intel *mpf, unsigned int early)
> >    */
> >   void __init default_get_smp_config(unsigned int early)
> >   {
> > -       struct mpf_intel *mpf = mpf_found;
> > +       struct mpf_intel *mpf;
> >
> >          if (!smp_found_config)
> >                  return;
> >
> > -       if (!mpf)
> > +       if (!mpf_base)
> >                  return;
> >
> >          if (acpi_lapic && early)
> > @@ -515,6 +516,12 @@ void __init default_get_smp_config(unsigned int early)
> >          if (acpi_lapic && acpi_ioapic)
> >                  return;
> >
> > +       mpf = early_memremap(mpf_base, sizeof(*mpf));
> > +       if (!mpf) {
> > +               pr_err("MPTABLE: error mapping MP table\n");
> > +               return;
> > +       }
> > +
> >          pr_info("Intel MultiProcessor Specification v1.%d\n",
> >                  mpf->specification);
> >   #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_32)
> > @@ -529,7 +536,7 @@ void __init default_get_smp_config(unsigned int early)
> >          /*
> >           * Now see if we need to read further.
> >           */
> > -       if (mpf->feature1 != 0) {
> > +       if (mpf->feature1) {
> >                  if (early) {
> >                          /*
> >                           * local APIC has default address
> > @@ -542,8 +549,10 @@ void __init default_get_smp_config(unsigned int early)
> >                  construct_default_ISA_mptable(mpf->feature1);
> >
> >          } else if (mpf->physptr) {
> > -               if (check_physptr(mpf, early))
> > +               if (check_physptr(mpf, early)) {
> > +                       early_memunmap(mpf, sizeof(*mpf));
> >                          return;
> > +               }
> >          } else
> >                  BUG();
> >
> > @@ -552,6 +561,8 @@ void __init default_get_smp_config(unsigned int early)
> >          /*
> >           * Only use the first configuration found.
> >           */
> > +
> > +       early_memunmap(mpf, sizeof(*mpf));
> >   }
> >
> >   static void __init smp_reserve_memory(struct mpf_intel *mpf)
> > @@ -561,15 +572,16 @@ static void __init smp_reserve_memory(struct mpf_intel *mpf)
> >
> >   static int __init smp_scan_config(unsigned long base, unsigned long length)
> >   {
> > -       unsigned int *bp = phys_to_virt(base);
> > +       unsigned int *bp;
> >          struct mpf_intel *mpf;
> > -       unsigned long mem;
> > +       int ret = 0;
> >
> >          apic_printk(APIC_VERBOSE, "Scan for SMP in [mem %#010lx-%#010lx]\n",
> >                      base, base + length - 1);
> >          BUILD_BUG_ON(sizeof(*mpf) != 16);
> >
> >          while (length > 0) {
> > +               bp = early_memremap(base, length);
> >                  mpf = (struct mpf_intel *)bp;
> >                  if ((*bp == SMP_MAGIC_IDENT) &&
> >                      (mpf->length == 1) &&
> > @@ -579,24 +591,26 @@ static int __init smp_scan_config(unsigned long base, unsigned long length)
> >   #ifdef CONFIG_X86_LOCAL_APIC
> >                          smp_found_config = 1;
> >   #endif
> > -                       mpf_found = mpf;
> > +                       mpf_base = base;
> >
> > -                       pr_info("found SMP MP-table at [mem %#010llx-%#010llx] mapped at [%p]\n",
> > -                               (unsigned long long) virt_to_phys(mpf),
> > -                               (unsigned long long) virt_to_phys(mpf) +
> > -                               sizeof(*mpf) - 1, mpf);
> > +                       pr_info("found SMP MP-table at [mem %#010lx-%#010lx] mapped at [%p]\n",
> > +                               base, base + sizeof(*mpf) - 1, mpf);
> >
> > -                       mem = virt_to_phys(mpf);
> > -                       memblock_reserve(mem, sizeof(*mpf));
> > +                       memblock_reserve(base, sizeof(*mpf));
> >                          if (mpf->physptr)
> >                                  smp_reserve_memory(mpf);
> >
> > -                       return 1;
> > +                       ret = 1;
> >                  }
> > -               bp += 4;
> > +               early_memunmap(bp, length);
> > +
> > +               if (ret)
> > +                       break;
> > +
> > +               base += 16;
> >                  length -= 16;
> >          }
> > -       return 0;
> > +       return ret;
> >   }
> >
> >   void __init default_find_smp_config(void)
> > @@ -838,29 +852,40 @@ static int __init update_mp_table(void)
> >          char oem[10];
> >          struct mpf_intel *mpf;
> >          struct mpc_table *mpc, *mpc_new;
> > +       unsigned long size;
> >
> >          if (!enable_update_mptable)
> >                  return 0;
> >
> > -       mpf = mpf_found;
> > -       if (!mpf)
> > +       if (!mpf_base)
> > +               return 0;
> > +
> > +       mpf = early_memremap(mpf_base, sizeof(*mpf));
> > +       if (!mpf) {
> > +               pr_err("MPTABLE: mpf early_memremap() failed\n");
> >                  return 0;
> > +       }
> >
> >          /*
> >           * Now see if we need to go further.
> >           */
> > -       if (mpf->feature1 != 0)
> > -               return 0;
> > +       if (mpf->feature1)
> > +               goto do_unmap_mpf;
> >
> >          if (!mpf->physptr)
> > -               return 0;
> > +               goto do_unmap_mpf;
> >
> > -       mpc = phys_to_virt(mpf->physptr);
> > +       size = get_mpc_size(mpf->physptr);
> > +       mpc = early_memremap(mpf->physptr, size);
> > +       if (!mpc) {
> > +               pr_err("MPTABLE: mpc early_memremap() failed\n");
> > +               goto do_unmap_mpf;
> > +       }
> >
> >          if (!smp_check_mpc(mpc, oem, str))
> > -               return 0;
> > +               goto do_unmap_mpc;
> >
> > -       pr_info("mpf: %llx\n", (u64)virt_to_phys(mpf));
> > +       pr_info("mpf: %llx\n", (u64)mpf_base);
> >          pr_info("physptr: %x\n", mpf->physptr);
> >
> >          if (mpc_new_phys && mpc->length > mpc_new_length) {
> > @@ -878,21 +903,32 @@ static int __init update_mp_table(void)
> >                  new = mpf_checksum((unsigned char *)mpc, mpc->length);
> >                  if (old == new) {
> >                          pr_info("mpc is readonly, please try alloc_mptable instead\n");
> > -                       return 0;
> > +                       goto do_unmap_mpc;
> >                  }
> >                  pr_info("use in-position replacing\n");
> >          } else {
> > +               mpc_new = early_memremap(mpc_new_phys, mpc_new_length);
> > +               if (!mpc_new) {
> > +                       pr_err("MPTABLE: new mpc early_memremap() failed\n");
> > +                       goto do_unmap_mpc;
> > +               }
> >                  mpf->physptr = mpc_new_phys;
> > -               mpc_new = phys_to_virt(mpc_new_phys);
> >                  memcpy(mpc_new, mpc, mpc->length);
> > +               early_memunmap(mpc, size);
> >                  mpc = mpc_new;
> > +               size = mpc_new_length;
> >                  /* check if we can modify that */
> >                  if (mpc_new_phys - mpf->physptr) {
> >                          struct mpf_intel *mpf_new;
> >                          /* steal 16 bytes from [0, 1k) */
> > +                       mpf_new = early_memremap(0x400 - 16, sizeof(*mpf_new));
> > +                       if (!mpf_new) {
> > +                               pr_err("MPTABLE: new mpf early_memremap() failed\n");
> > +                               goto do_unmap_mpc;
> > +                       }
> >                          pr_info("mpf new: %x\n", 0x400 - 16);
> > -                       mpf_new = phys_to_virt(0x400 - 16);
> >                          memcpy(mpf_new, mpf, 16);
> > +                       early_memunmap(mpf, sizeof(*mpf));
> >                          mpf = mpf_new;
> >                          mpf->physptr = mpc_new_phys;
> >                  }
> > @@ -909,6 +945,12 @@ static int __init update_mp_table(void)
> >           */
> >          replace_intsrc_all(mpc, mpc_new_phys, mpc_new_length);
> >
> > +do_unmap_mpc:
> > +       early_memunmap(mpc, size);
> > +
> > +do_unmap_mpf:
> > +       early_memunmap(mpf, sizeof(*mpf));
> > +
> >          return 0;
> >   }
> >
> > --
> > 1.9.1
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