| Message ID | 20231016132819.1002933-8-michael.roth@amd.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support | expand |
On Mon, Oct 16, 2023 at 08:27:36AM -0500, Michael Roth wrote: > From: Brijesh Singh <brijesh.singh@amd.com> > > The snp_lookup_page_in_rmptable() can be used by the host to read the RMP $ git grep snp_lookup_page_in_rmptable $ Stale commit message. And not very telling. Please rewrite. > entry for a given page. The RMP entry format is documented in AMD PPR, see > https://bugzilla.kernel.org/attachment.cgi?id=296015. <--- Brijesh's SOB comes first here if he's the primary author. > Co-developed-by: Ashish Kalra <ashish.kalra@amd.com> > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> > [mdr: separate 'assigned' indicator from return code] > Signed-off-by: Michael Roth <michael.roth@amd.com> > --- > arch/x86/include/asm/sev-common.h | 4 +++ > arch/x86/include/asm/sev-host.h | 22 +++++++++++++ > arch/x86/virt/svm/sev.c | 53 +++++++++++++++++++++++++++++++ > 3 files changed, 79 insertions(+) > create mode 100644 arch/x86/include/asm/sev-host.h > > diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h > index b463fcbd4b90..1e6fb93d8ab0 100644 > --- a/arch/x86/include/asm/sev-common.h > +++ b/arch/x86/include/asm/sev-common.h > @@ -173,4 +173,8 @@ struct snp_psc_desc { > #define GHCB_ERR_INVALID_INPUT 5 > #define GHCB_ERR_INVALID_EVENT 6 > > +/* RMP page size */ > +#define RMP_PG_SIZE_4K 0 RMP_PG_LEVEL_4K just like the generic ones. > +#define RMP_TO_X86_PG_LEVEL(level) (((level) == RMP_PG_SIZE_4K) ? PG_LEVEL_4K : PG_LEVEL_2M) What else is there besides X86 PG level? IOW, RMP_TO_PG_LEVEL simply. > + > #endif > diff --git a/arch/x86/include/asm/sev-host.h b/arch/x86/include/asm/sev-host.h Nah, we don't need a third sev header: arch/x86/include/asm/sev-common.h arch/x86/include/asm/sev.h arch/x86/include/asm/sev-host.h Put it in sev.h pls. sev-common.h should be merged into sev.h too unless there's a compelling reason not to which I don't see atm. > new file mode 100644 > index 000000000000..4c487ce8457f > --- /dev/null > +++ b/arch/x86/include/asm/sev-host.h ... > diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c > index 8b9ed72489e4..7d3802605376 100644 > --- a/arch/x86/virt/svm/sev.c > +++ b/arch/x86/virt/svm/sev.c > @@ -53,6 +53,9 @@ struct rmpentry { > */ > #define RMPTABLE_CPU_BOOKKEEPING_SZ 0x4000 > > +/* Mask to apply to a PFN to get the first PFN of a 2MB page */ > +#define PFN_PMD_MASK (~((1ULL << (PMD_SHIFT - PAGE_SHIFT)) - 1)) GENMASK_ULL > static struct rmpentry *rmptable_start __ro_after_init; > static u64 rmptable_max_pfn __ro_after_init; > > @@ -237,3 +240,53 @@ static int __init snp_rmptable_init(void) > * the page(s) used for DMA are hypervisor owned. > */ > fs_initcall(snp_rmptable_init); > + > +static int rmptable_entry(u64 pfn, struct rmpentry *entry) The signature of this one should be: static struct rmpentry *get_rmp_entry(u64 pfn) and the callers should use the IS_ERR* macros to check whether it returns a valid pointer or a negative value for error. Ditto for the other two functions here. > + if (WARN_ON_ONCE(pfn > rmptable_max_pfn)) > + return -EFAULT; > + > + *entry = rmptable_start[pfn]; This wants to be called rmptable[] then. > + > + return 0; > +} > + > +static int __snp_lookup_rmpentry(u64 pfn, struct rmpentry *entry, int *level) > +{ > + struct rmpentry large_entry; > + int ret; > + > + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) > + return -ENXIO; ENODEV or so. > + > + ret = rmptable_entry(pfn, entry); > + if (ret) > + return ret; > + > + /* > + * Find the authoritative RMP entry for a PFN. This can be either a 4K > + * RMP entry or a special large RMP entry that is authoritative for a > + * whole 2M area. > + */ > + ret = rmptable_entry(pfn & PFN_PMD_MASK, &large_entry); > + if (ret) > + return ret; > + > + *level = RMP_TO_X86_PG_LEVEL(large_entry.pagesize); > + > + return 0; > +} > + > +int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) > +{ > + struct rmpentry e; > + int ret; > + > + ret = __snp_lookup_rmpentry(pfn, &e, level); > + if (ret) > + return ret; > + > + *assigned = !!e.assigned; > + return 0; > +} > +EXPORT_SYMBOL_GPL(snp_lookup_rmpentry); > -- Thx.
On Tue, Nov 14, 2023 at 03:24:42PM +0100, Borislav Petkov wrote: > On Mon, Oct 16, 2023 at 08:27:36AM -0500, Michael Roth wrote: > > From: Brijesh Singh <brijesh.singh@amd.com> > > > > The snp_lookup_page_in_rmptable() can be used by the host to read the RMP > > $ git grep snp_lookup_page_in_rmptable > $ > > Stale commit message. And not very telling. Please rewrite. > > > entry for a given page. The RMP entry format is documented in AMD PPR, see > > https://bugzilla.kernel.org/attachment.cgi?id=296015. > > <--- Brijesh's SOB comes first here if he's the primary author. > > > Co-developed-by: Ashish Kalra <ashish.kalra@amd.com> > > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> > > [mdr: separate 'assigned' indicator from return code] > > Signed-off-by: Michael Roth <michael.roth@amd.com> > > --- > > arch/x86/include/asm/sev-common.h | 4 +++ > > arch/x86/include/asm/sev-host.h | 22 +++++++++++++ > > arch/x86/virt/svm/sev.c | 53 +++++++++++++++++++++++++++++++ > > 3 files changed, 79 insertions(+) > > create mode 100644 arch/x86/include/asm/sev-host.h > > > > diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h > > index b463fcbd4b90..1e6fb93d8ab0 100644 > > --- a/arch/x86/include/asm/sev-common.h > > +++ b/arch/x86/include/asm/sev-common.h > > @@ -173,4 +173,8 @@ struct snp_psc_desc { > > #define GHCB_ERR_INVALID_INPUT 5 > > #define GHCB_ERR_INVALID_EVENT 6 > > > > +/* RMP page size */ > > +#define RMP_PG_SIZE_4K 0 > > RMP_PG_LEVEL_4K just like the generic ones. I've moved this to sev.h, but it RMP_PG_SIZE_4K is already defined there and used by a bunch of guest code so it's a bit out-of-place to update those as part of this patchset. I can send a follow-up series to clean up some of the naming and get rid of sev-common.h > > > +#define RMP_TO_X86_PG_LEVEL(level) (((level) == RMP_PG_SIZE_4K) ? PG_LEVEL_4K : PG_LEVEL_2M) > > What else is there besides X86 PG level? > > IOW, RMP_TO_PG_LEVEL simply. Make sense. > > > + > > #endif > > diff --git a/arch/x86/include/asm/sev-host.h b/arch/x86/include/asm/sev-host.h > > Nah, we don't need a third sev header: > > arch/x86/include/asm/sev-common.h > arch/x86/include/asm/sev.h > arch/x86/include/asm/sev-host.h > > Put it in sev.h pls. Done. > > sev-common.h should be merged into sev.h too unless there's a compelling > reason not to which I don't see atm. Doesn't seem like it would be an issue, maybe some fallout from any files that previously only included sev-common.h and now need to pull in guest struct definitions as well, but those definitions don't have a lot of external dependencies so don't anticipate any header include hellishness. I'll send that as a separate follow-up, along with some of the renames you suggested above since they'll touch guest code and create unecessary churn for SNP host support. Thanks, Mike > > -- > > Thx. > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette
On Mon, Dec 18, 2023 at 09:31:50PM -0600, Michael Roth wrote: > I've moved this to sev.h, but it RMP_PG_SIZE_4K is already defined there > and used by a bunch of guest code so it's a bit out-of-place to update > those as part of this patchset. I can send a follow-up series to clean up > some of the naming and get rid of sev-common.h Yap, good idea. > Doesn't seem like it would be an issue, maybe some fallout from any > files that previously only included sev-common.h and now need to pull in > guest struct definitions as well, but those definitions don't have a lot > of external dependencies so don't anticipate any header include > hellishness. I'll send that as a separate follow-up, along with some of > the renames you suggested above since they'll touch guest code and > create unecessary churn for SNP host support. OTOH, people recently have started looking at including only that stuff which is really used so having a single header would cause more preprocessing effort. I'm not too crazy about it as the preprocessing overhead is barely measurable so might as well have a single header and then split it later... Definitely something for the after-burner and not important right now. Thx.
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h index b463fcbd4b90..1e6fb93d8ab0 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -173,4 +173,8 @@ struct snp_psc_desc { #define GHCB_ERR_INVALID_INPUT 5 #define GHCB_ERR_INVALID_EVENT 6 +/* RMP page size */ +#define RMP_PG_SIZE_4K 0 +#define RMP_TO_X86_PG_LEVEL(level) (((level) == RMP_PG_SIZE_4K) ? PG_LEVEL_4K : PG_LEVEL_2M) + #endif diff --git a/arch/x86/include/asm/sev-host.h b/arch/x86/include/asm/sev-host.h new file mode 100644 index 000000000000..4c487ce8457f --- /dev/null +++ b/arch/x86/include/asm/sev-host.h @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * AMD SVM-SEV Host Support. + * + * Copyright (C) 2023 Advanced Micro Devices, Inc. + * + * Author: Ashish Kalra <ashish.kalra@amd.com> + * + */ + +#ifndef __ASM_X86_SEV_HOST_H +#define __ASM_X86_SEV_HOST_H + +#include <asm/sev-common.h> + +#ifdef CONFIG_KVM_AMD_SEV +int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level); +#else +static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENXIO; } +#endif + +#endif diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c index 8b9ed72489e4..7d3802605376 100644 --- a/arch/x86/virt/svm/sev.c +++ b/arch/x86/virt/svm/sev.c @@ -53,6 +53,9 @@ struct rmpentry { */ #define RMPTABLE_CPU_BOOKKEEPING_SZ 0x4000 +/* Mask to apply to a PFN to get the first PFN of a 2MB page */ +#define PFN_PMD_MASK (~((1ULL << (PMD_SHIFT - PAGE_SHIFT)) - 1)) + static struct rmpentry *rmptable_start __ro_after_init; static u64 rmptable_max_pfn __ro_after_init; @@ -237,3 +240,53 @@ static int __init snp_rmptable_init(void) * the page(s) used for DMA are hypervisor owned. */ fs_initcall(snp_rmptable_init); + +static int rmptable_entry(u64 pfn, struct rmpentry *entry) +{ + if (WARN_ON_ONCE(pfn > rmptable_max_pfn)) + return -EFAULT; + + *entry = rmptable_start[pfn]; + + return 0; +} + +static int __snp_lookup_rmpentry(u64 pfn, struct rmpentry *entry, int *level) +{ + struct rmpentry large_entry; + int ret; + + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) + return -ENXIO; + + ret = rmptable_entry(pfn, entry); + if (ret) + return ret; + + /* + * Find the authoritative RMP entry for a PFN. This can be either a 4K + * RMP entry or a special large RMP entry that is authoritative for a + * whole 2M area. + */ + ret = rmptable_entry(pfn & PFN_PMD_MASK, &large_entry); + if (ret) + return ret; + + *level = RMP_TO_X86_PG_LEVEL(large_entry.pagesize); + + return 0; +} + +int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) +{ + struct rmpentry e; + int ret; + + ret = __snp_lookup_rmpentry(pfn, &e, level); + if (ret) + return ret; + + *assigned = !!e.assigned; + return 0; +} +EXPORT_SYMBOL_GPL(snp_lookup_rmpentry);